Dermatology

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12.1 Dermatology

Roderic Phillips, David Orchard, Mike Starr

Essentials

1 Look at the rash.

• Are there any blisters? Finding fluid-filled lesions greatly narrows the range of possible diagnoses.
• Is the rash red? Redness is from haemoglobin. Most red rashes blanch, i.e. the redness disappears with pressure. If not, the haemoglobin is outside the blood vessels giving purpura.
• Is the rash scaly? If so, the epidermis is involved in the disease process. The epidermis may be broken to give weeping, crusting or fissures (‘eczematous rash’), or it may be intact (‘red scaly rash’).

2 Examine all the skin including the anogenital region.
3 Do not ignore a skin condition even if unrelated to the emergency visit. You may not deal with it yourself but you can organise appropriate follow up for it.

Introduction

Approximately 65 000 children a year attend the emergency department (ED) at the Royal Children’s Hospital in Melbourne and about 15 000 of these have some skin findings relevant to their visit. For 4000 children (6%), skin findings are a primary reason for their visit. These figures are likely to be representative of other tertiary teaching hospital EDs in Australasia. Diagnosing and managing these children requires a careful history and astute observation, particularly focusing on the appearance, site and development of their rashes.

For children who present to the ED with the primary symptom in another organ, the physician has an opportunity to observe cutaneous signs of disease, which may be relevant or may be coincidental to the child’s presentation, for example, a 5-year-old boy (Fig. 12.1.1) who presents with gastroenteritis. You notice the mild comedonal rash on his forehead and recognise that this is unusual at this age. Examination shows that he is tall for his age and has inappropriate penile (but not testicular) growth. His hyperadrenergic state can be investigated and treated years before it might otherwise have been recognised.

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Fig. 12.1.1 Mild prepubertal acne on the forehead of a 5-year-old boy who presented with the unrelated problem of gastroenteritis. Examination and investigation confirmed that he had a variant of congenital adrenal hyperplasia requiring treatment.

The discussion of diseases in this chapter is based on the features of the presenting rash and follows the algorithm given in Essentials. Diseases are grouped under their main morphology, e.g. vesicular, papular, eczematous, or purpuric. Mouth, anogenital, hair and nail problems are considered separately.

Erythroderma and skin failure

Erythroderma is one form of skin failure and refers to any condition that causes most of the skin surface to become red, often with some degree of scaling. Skin failure is rarely taught as a concept but is analogous to failure of any other organ system. Skin failure refers to the inability of the skin to adequately perform its functions, such as fluid and electrolyte balance, temperature control and protection from infection. Any child presenting with extensive areas of skin pathology or skin loss has some degree of skin failure. This may be well tolerated in otherwise healthy children but may be life threatening, especially in infants and those children with associated disorders.

Children presenting with erythroderma will usually be found to have one of the following: atopic eczema (with or without secondary staphylococcal infection); an allergic reaction; or sepsis with toxin-mediated skin involvement. Less common causes include: psoriasis; pityriasis rubra pilaris; several forms of inherited ichthyosis; some other genodermatoses; and internal lymphoid malignancies. In 10–20% of children with erythroderma, no cause can be found.

Management

• The aim is to restore and maintain the core functions of skin. Many sensible management decisions can be made before the diagnosis is clear.
• Have a low threshold for admission to hospital.
• Restore skin-barrier function by using an ointment emollient frequently.
• Monitor temperature, as the child may readily become hypothermic or, less commonly, hyperthermic.
• Monitor fluids and electrolytes.
• Monitor cardiac output, particularly if the child has known cardiac pathology.
• Skin and/or systemic sepsis may have caused the skin failure or may be secondary to it. Temperature control may be affected, so fever may not be present. Have a low threshold for giving systemic antibiotics, particularly to cover Staphylococcus aureus and streptococcal species.
• Local or systemic pain relief may be required.
• Cease all non-essential drugs.
• Identify and treat the underlying cause.
• Manage any associated conditions (e.g. diabetes, renal failure, congenital heart problems, metabolic disorders).

Vesiculobullous rashes

Vesicles are usually caused by infections (herpes simplex virus, varicella zoster virus, enterovirus, tinea, scabies or impetigo) or contact dermatitis. Also, consider drug reactions, erythema multiforme and photosensitivity. Dermatitis herpetiformis is a rare cause of itchy vesicles and papules. Larger blisters occur with staphylococcal infections, tinea, erythema multiforme, Stevens–Johnson syndrome, immune-mediated blistering disorders, arthropod bites, contact dermatitis, fixed and bullous drug reactions, mastocytosis, burns or trauma.

Many vesicles and blisters are fragile and rupture easily. A vesicular disease may present with a number of shallow monomorphic erosions but no vesicles. A bullous disease may present with several larger shallow erosions with surrounding loose epithelium but no bullae. Vesicles present for more than a couple of days become cloudy and vesiculopustular.

Varicella (chickenpox)

Varicella is caused by infection with varicella zoster virus. It usually occurs in children less than 15 years of age, and is highly contagious. The incubation period is 2–3 weeks. The contagious period begins 2 days before the rash and continues until the lesions are crusted. Clinical disease begins with a fever and malaise but these are usually mild. Lesions on the skin appear initially as erythematous macules, rapidly becoming small vesicles and then crusting. Over the next few days, anything from a few to hundreds of lesions may develop, initially on the face and trunk and gradually spreading onto the extremities. Superficial ulcers may be seen on all mucosal surfaces. Itch is not always present but may be marked. Vaccinated children may develop attenuated disease with fewer lesions and without constitutional symptoms. Diagnosis is clinical but can be confirmed by serology or immunofluorescence of vesicular scrapings for varicella-zoster virus antigen. Complete resolution occurs in most children but some scarring is common.

Children with varicella usually remain systemically well and afebrile after the first few days. If persistent fever and malaise is present, search for complications. In previously well children, the most common complications are:

• Bacterial skin infection with group A Streptococci or Staphylococcus aureus. Look for bullous, indurated, spreading or cellulitic lesions. Treat with oral antibiotics.
• Central nervous system (CNS) dysfunction. Encephalitis, meningitis, transverse myelitis, Guillain–Barré syndrome or Reye’s syndrome (sudden onset of vomiting, coma and liver abnormalities) may occur. Cerebrospinal fluid (CSF) analysis, including polymerase chain reaction (PCR) assay for varicella-zoster virus DNA may be useful in suspected encephalitis.
• Pneumonia. Cough and respiratory distress begin a couple of days after onset of the rash.
• Cerebellar ataxia may appear as the rash is clearing and resolve within weeks.

In neonates, immunocompromised children and adolescents, varicella can be more severe and occasionally fatal.

Management

• Treatment of otherwise well children with varicella is supportive with bland emollients and oral antihistamine if necessary. If the child is unwell, look for secondary complications.
• Avoid aspirin or other salicylates because of the association with Reye’s syndrome.
• Treat secondary skin infection with cefalexin 30 mg kg−1 (max 500 mg) three times daily.
• Immunocompromised children should be treated with intravenous aciclovir 20 mg kg–1 per dose (2–12 weeks), 500 mg m–2 per dose (12 weeks–12 years), 10 mg kg–1 per dose (adult) 8-hourly given over 1 hour.
• Premature neonates (less than 1 month old) with varicella should be treated with intravenous aciclovir.
• Term neonates should be admitted, and treated with aciclovir if they have severe disease.
• Give zoster immune globulin to at-risk contacts (immunocompromised children, those on prednisolone 2 mg kg–1 day–1 or more, newborns of mothers who have varicella any time from 5 days before until 2 days after delivery). Give within 4 days of exposure (6 mL for adults, 4 mL for children 6–12 years of age, 2 mL for children up to 5 years of age).
• Exclude from school until all lesions are crusted.
• Offer varicella-zoster vaccine to non-immune contacts – the vaccine has been shown to prevent or attenuate infection if given within 5 days of exposure.

Zoster

Zoster is uncommon in childhood but can occur at any age, even in the neonatal period. It occurs in children who have previously had primary varicella infection. Zoster in a young child is usually associated with primary varicella having occurred in infancy. The primary infection may have been mild and may even have gone unnoticed because of maternally-acquired IgG.

Radicular pain may be the first symptom of zoster but pain is less common than in adults and may not be present. Vesicles on an erythematous background appear in one or more groups aligned in a dermatomal distribution, frequently with a striking midline cut-off. The affected area can be an isolated group of a few vesicles suggestive of herpes simplex virus infection. Alternatively, there may be extensive involvement of one or more dermatomes. Lesions continue to appear for a few days and then resolve over 2 weeks, generally without sequelae. Postherpetic neuralgia is very uncommon after childhood zoster.

Complications include generalised dissemination during the first week of the rash, sometimes with pulmonary or brain involvement. This can be seen in both normal and immunocompromised children. Zoster on the head is occasionally accompanied by an aseptic meningitis, which resolves fully without treatment. Zoster lesions on the tip of the nose imply involvement of the nasociliary branch of the ophthalmic nerve and may accompany ocular involvement including keratitis and conjunctivitis. Facial nerve palsy and ear involvement can occur (Ramsay Hunt syndrome).

Immunocompromised children are much more likely to develop zoster. In such cases, zoster may be severe, extensive and prolonged. Significant dermatomal scarring can result.

Management

• If the diagnosis is unclear, collect epithelial cells from the base and roof of the vesicles for immunofluorescence and viral culture. This is not ‘just a swab’ and it requires some persistence to collect enough cells.
• In an otherwise well child, the occurrence of typical zoster does not require investigation for underlying immunodeficiency states. However, unusually severe or extensive zoster should raise this possibility.
• If a child has underlying chronic illness or immunodeficiency, give intravenous aciclovir or oral famciclovir or valaciclovir. Oral antiviral agents can be considered in older adolescents but are not generally indicated in an otherwise well child as the risk of significant symptoms or post-herpetic neuralgia is very small.

Hand, foot and mouth disease

Hand, foot and mouth disease is one presentation of enteroviral infection, usually Coxsackie A16 virus. There may be a mild prodrome of fever, malaise and sore throat. Discrete vesicles about 6 mm in diameter on an erythematous base appear first in the mouth, sparing the lips and usually sparing the gingiva. One to 2 days later, 3–7 mm vesiculopustules on an erythematous base appear on the palms, soles and around the fingers and toes. Lesions are also often found on the buttocks. They are often greyish and oval rather than circular in shape. In some cases, the mouth, hands or feet may not be involved. Resolution occurs within a week. The incubation period is about 5 days and epidemics are common. Virus is excreted in the faeces for weeks and exclusion is not recommended. Supportive care leads to complete recovery.

Herpes simplex infection (HSV)

Herpes simplex infection in childhood is common. Intrauterine, intrapartum and neonatal infection are considered elsewhere. Primary herpes infection after the neonatal period may be either primary herpetic gingivostomatitis or primary cutaneous herpes simplex. In children with impaired immune function, HSV infection can present as indolent, slowly growing, irregular ulcers. Most HSV infections in children are caused by HSV-1, but HSV-2 may also cause gingival and cutaneous infection.

Primary cutaneous herpes simplex can present at any age. There may be a history of a family member with a recently activated herpes simplex lesion on the lip (‘cold sore’). However, the virus is ubiquitous and transmission more often occurs from an unknown source. At least 50% of the population have HSV-1 antibodies, and many of these have never had an obvious infection. Painful grouped vesicles on an erythematous base can appear at any site. Multiple lesions rupture, crust and coalesce into larger erosions with scalloped edges. There may be associated fever, malaise and lymphadenopathy.

Management

Management consists of the following;

• supportive care;
• bathing of crusts;
• analgesia;
• aciclovir is not routinely indicated unless risk factors for complications exist (e.g. underlying disease, immunosuppression).

Recurrent cutaneous herpes simplex can occur weeks or months after the primary episode. Recurrences usually get milder and less common with time but exacerbations can occur throughout childhood and later life (Fig. 12.1.2). Recurrences can lead to significant time off school. Antiviral prophylaxis may reduce the frequency and severity of recurrences, and should be used if recurrences are frequent or debilitating.

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Fig. 12.1.2 (A) This erythematous, slightly vesicular rash around the eye of a 4-year-old boy had appeared over 12 hours. Because his other eye was blind, he was treated with oral aciclovir. Immunofluorescence confirmed herpes simplex virus. (B) One day later.

HSV infection can involve the fingers, especially the thumbs and index fingers (herpetic whitlow). At these sites, the thick skin does not readily rupture and children present with painful, coalesced pustular collections, often misinterpreted as bacterial abscesses. Any history of ‘abscesses’ occurring at the same site on a finger on more than one occasion is suggestive of herpes simplex. Management includes taking a swab for immunofluorescence and viral culture to confirm the diagnosis, analgesia and supportive care.

Eczema herpeticum

Herpes simplex infection in children with eczema is quite common. It occurs in children with any severity of eczema including children with mild eczema under excellent control. Many cases are misdiagnosed either as an exacerbation of the eczema or as bacterial infection (Fig. 12.1.3). Grouped vesicles may be prominent, but more often vesicles are rudimentary or absent and the infection may present as a group of shallow 2–4 mm monomorphic erosions on an inflamed base. In more severe cases, evolution is rapid and large crops of vesicles can arise daily. Ulcers may coalesce into larger erosions with scalloped edges. The infected area may not be painful or itchy.

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Fig. 12.1.3 Eczema herpeticum. Typical monomorphic vesicles can be seen away from the central weeping area.

In an atopic child, a high index of suspicion is needed about any patch of skin where small erosions or crusts are present and not responding to standard eczema therapy with moisturisers and topical cortisone derivatives. One reason for the under diagnosis of this condition is that even without treatment, resolution usually occurs in 1–4 weeks. However, dissemination may occur, leading to multifocal and extensive erosions, malaise and secondary bacterial infection. In the past, disseminated eczema herpeticum had a significant mortality but this has declined with the recognition and aggressive treatment of secondary bacterial infections.

After complete resolution, recurrences may occur at the same or different sites, sometimes as often as every few weeks. Recurrences can be widespread and severe but usually decrease in severity over 1 to 2 years.

Management

• Clinical differentiation between herpetic and bacterial infection may be difficult; investigation and empiric treatment for both may be necessary.
• Collect epithelial cells from the base and roof of the vesicles for HSV immunofluorescence and viral culture. This requires some persistence to collect enough cells.
• Local stable disease in an otherwise well child requires regular observation but does not need antiviral therapy.
• Milder cases demonstrating progression or facial involvement can be managed with oral aciclovir.
• Admission to hospital and treatment with intravenous aciclovir (20 mg kg–1 per dose (2–12 weeks), 500 mg m–2 per dose (12 weeks–12 years), 10 mg kg–1 per dose (adult) 8-hourly should be considered for children with any of fever, multiple sites of cutaneous herpes infection, widespread eczema, eye involvement, immunosuppression or age less than 6 months.
• Secondary bacterial infection is common. Swabs for microscopy and culture are usually unhelpful. If there is any suspicion of bacterial infection, add intravenous flucloxacillin 50 mg kg−1 (max 2 g) 6-hourly or oral cefalexin 30 mg kg−1 (max 500 mg) three times daily. Soak to remove excessive crusts.
• Monitor for eye involvement, particularly scleral redness. If present, this should be managed with topical or systemic aciclovir, or both, and urgent review by an ophthalmologist.
• The underlying eczema can be treated with moisturiser or wet dressings until the herpetic scabs have been removed and then it is important to restart topical cortisone treatment.
• Antiviral prophylaxis may reduce the frequency and severity of recurrences and is often warranted in older children with recurrent eczema herpeticum.

Impetigo (school sores)

This is caused by Staphylococcus aureus or group A Streptococcus or both.

Non-bullous impetigo presents initially as small erythematous vesicles that rapidly rupture to form yellow-crusted lesions, commonly on the face.

Bullous impetigo is due to Staphylococcus aureus and presents as flaccid blisters on normal skin. Lesions are rounded and well demarcated and may be single, grouped or widespread. Their onset and spread may be rapid or occur over days. New blisters appear and existing blisters rupture to give shallow moist erosions that can be many centimetres in size. There is often loose epithelium and/or brown crusting peripherally and some degree of central healing (Fig. 12.1.4). In more chronic cases, lesions may appear annular.

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Fig. 12.1.4 Bullous impetigo in a 7-year-old girl.

Impetigo is often secondary to itchy conditions such as scabies infection (especially hand impetigo), atopic eczema and head lice.

Post-streptococcal glomerulonephritis may occur in the ensuing 2 months. Contrary to long-held beliefs, it now seems likely that chronic streptococcal impetigo may also be a precursor of rheumatic heart disease in communities where medical conditions are poor and skin hygiene is suboptimal.1

Management

• Swab for microscopy and culture if the diagnosis is unclear or in widespread or complicated disease.
• Bathe off crusts.
• Apply topical mupirocin 2% ointment 8-hourly if very localised, or oral cefalexin 30 mg kg−1 (maximum 500 mg) three times daily if extensive.
• Isolate the child from other children or from sick adults unless all lesions are covered or antibiotic treatment has commenced.
• Treat any underlying condition such as scabies or eczema.
• Blisters or erosions often continue to occur for a couple of days after antibiotic therapy. If new blisters continue to form after this time, they may be caused by resistant Staphylococcus aureus infection, or the child may have an immune-mediated blistering disorder rather than impetigo.
• Children with chronic impetigo should be examined for any signs of heart disease. Families should be aware that rheumatic heart disease may be delayed by some years in this setting. Older siblings are likely to have had chronic impetigo in the past and therefore to also be at risk of heart disease and should be examined.
• In any child with chronic impetigo where ongoing care may be suboptimal, review with urinalysis to monitor for glomerulonephritis is warranted. In other cases, families should be aware of the possibility of renal involvement.

Staphylococcal scalded skin syndrome

This is usually seen in younger children or children with renal impairment. It is mediated by an epidermolytic toxin released from an often insignificant staphylococcal focus (e.g. eyes, nose or skin). Fever and tender erythematous skin are early features. Exudation and crusting develop, especially around the mouth. Wrinkling, flaccid bullae and exfoliation of the skin are seen and can be extensive. Nikolsky sign is present (‘normal’ skin separates if rubbed). Blisters are very superficial and heal without scarring.

Management

• Admit to hospital. Monitor temperature, fluids and electrolytes if large areas are involved. Increase oral (or intravenous) fluids to increase toxin excretion. Give analgesia.
• Consider alternative diagnoses including Stevens–Johnson syndrome and toxic epidermal necrolysis. If the diagnosis is unclear, a skin biopsy will confirm the diagnosis by showing the split is in the granular layer in the upper epidermis.
• Flucloxacillin 50 mg kg–1 (maximum 2 g) IV 6-hourly if there is evidence of sepsis or systemic involvement.
• Look for a focus of infection. Drain any foci of pus if present.
• Handle skin carefully and use an emollient ointment.

Erythema multiforme

This is a specific hypersensitivity syndrome that occurs at any age, often preceded by facial herpes simplex virus infection. It is over-diagnosed in emergency departments. Most children diagnosed with erythema multiforme actually have urticaria, often with large lesions with annular or polycyclic borders. In erythema multiforme, the primary lesions are red papules, usually symmetrical and involving the forearms, palms, feet, face, neck and trunk. They can be found anywhere. There may be few or many lesions. At least some of the papules will form classical target lesions – these have an inner zone of epidermal injury (purpura, necrosis or vesicle), an outer zone of erythema and sometimes a middle zone of pale oedema (Fig. 12.1.5). These papules and target lesions are not migratory. The involvement of mucous membranes is common but unlike Stevens–Johnson syndrome, is limited to isolated patches. Most cases are caused by herpes simplex virus, including most of the cases that occur without prior symptoms. Drugs are an uncommon cause. Erythema multiforme does not evolve into Stevens–Johnson syndrome. They are different conditions.

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Fig. 12.1.5 Erythema multiforme target lesions.

Management

• Fluid maintenance.
• Analgesia if required.
• Apply emollient ointment to the lips, if needed.
• If the condition is recurrent, it is highly likely to be related to herpes simplex virus. Prophylactic aciclovir prevents recurrences and should be considered if recurrences are frequent, severe and affecting the quality of life.
• Prednisolone alleviates symptoms but probably prolongs the duration of the condition and may cause recurrence of herpes simplex virus infection.

Stevens–Johnson syndrome/toxic epidermal necrolysis

Stevens–Johnson syndrome and toxic epidermal necrolysis are believed by many to be variants of the one condition. Most cases are thought to be triggered by medications, especially antibiotics (sulfonamides, penicillins), anticonvulsants (lamotrigine) and non-steroidal anti-inflammatory drugs. Mycoplasma and other infections may be the cause in some children. Fever, myalgia, arthralgia, headache and other organ involvement are usually present as a prodromal illness for several days. The rash evolves suddenly, characterised by widespread blisters on an erythematous or purpuric macular background, often with extensive mucous membrane haemorrhagic crusting. Lesions are usually on the face and trunk or generalised rather than acral, and typical target lesions are not seen. There may be tender erythematous areas with a positive Nikolsky sign (‘normal’ skin separates if rubbed). Mucous membrane involvement can be extensive, severe and painful. Conjunctivitis, corneal ulceration and blindness can occur. Anogenital lesions can lead to urinary retention.

Management

• See general advice under ‘skin failure’.
• Admit to hospital. A multidisciplinary approach including dermatology, paediatrics, ophthalmology, surgery and paediatric intensive care is required. Good nursing care is paramount. In severe cases, nurse in a specialised burns unit.
• Apply emollient ointment to the skin, lips and anogenital areas – this may be required many times a day.
• Regular eye examination with specialist review is required. Topical steroid eye drops may be needed.
• Give IV immunoglobulin 2 g kg−1. Commence ciclosporin (5–6 mg kg−1 day−1 orally for a few days, then taper to 3–5 mg kg−1 day−1 for 2–3 weeks). Data about the efficacy of any treatment regimens are limited but are sufficent to justify treatment. Stevens–Johnson syndrome has a significant mortality and has a high rate of permanent visual scarring including blindness as well as other problems.
• Maintain good nutrition, with nasogastric feeding if needed.
• Intubation may be needed if the child is unable to protect the airway because of severe oropharyngeal involvement.

Note: Stevens–Johnson syndrome is not severe erythema multiforme. They are distinct conditions. Permanent sequelae are rarely seen in severe erythema multiforme and concurrent drug use is unlikely to be the cause. Skin lesion distribution and morphology are the best discriminating factors. Mucous membrane involvement can be seen in both conditions but is confluent in Stevens-Johnson syndrome.

Dermatitis herpetiformis

Dermatitis herpetiformis is an uncommon autoimmune blistering disease that may present at any age as itchy papules or vesicles. Rapid excoriation means that intact vesicles are rarely seen. Lesions occur on extensor surfaces of the limbs, buttocks, trunk and scalp. Most patients have gluten enteropathy (coeliac disease) and may have abdominal discomfort, diarrhoea or anaemia. Some degree of villous atrophy will be seen on small bowel biopsy in most cases, but coeliac disease is often asymptomatic at the time of presentation of dermatitis herpetiformis. Growth retardation has been reported with dermatitis herpetiformis, probably secondary to intestinal involvement.

Recurrence some years after successful treatment has been reported.

Management

• Perilesional skin should be biopsied for immunofluorescence to demonstrate the diagnostic granular IgA deposition.
• Investigate for coeliac disease with total IgA, anti-tissue transglutaminase IgA and anti-deamidated gliadin IgA. Anti-transglutaminase antibodies are the most specific for dermatitis herpetiformis. A small bowel biopsy is required but may be equivocal early in the disease course.
• Anaemia, usually megaloblastic secondary to malabsorption, may be found.

Skin lesions (but not intestinal symptoms) respond well to dapsone, but haemolysis and other side effects can limit its use. A gluten-free diet normalises gut function and, in most children, leads to eventual clearing of skin lesions.

Other immune-mediated blistering disorders

As with dermatitis herpetiformis, the many diseases in this group are characterised by circulating autoantibodies directed against one or other of the structural proteins that give the epidermis its integrity. All are uncommon in childhood, linear IgA dermatosis (chronic bullous disease of childhood) being the most common. An immune-mediated blistering disorder should be considered in an otherwise well child if vesicles, blisters, or crusted erosions continue to appear for more than a couple of weeks.

If there is a split below the basement membrane, lesions may be tense, long-lasting bullae, as seen in dermatitis herpetiformis, linear IgA dermatosis, systemic lupus erythematosus and pemphigoid. If the split is higher in the epidermis, lesions are flaccid, short-lived blisters that rapidly give crusted erosions with loose epithelium around the edges. These are seen in pemphigus variants. Lesions can mimic local or generalised impetigo. Mucous membranes may be involved. Despite the widespread and often dramatic appearance of the rash, the child is usually well. Accurate diagnosis always requires histology and immunofluorescence in addition to clinical findings. Management requires immunosuppressive therapy and long-term follow up.

Sunburn and photosensitivity

Excessive solar radiation to the skin causes erythema and tenderness commencing at least half an hour after the beginning of the exposure. Tenderness worsens for a day and resolves in 4 days. In more severe cases, oedema and blistering may be widespread. Healing is accompanied by desquamation and intense itch. Sunburn occurs more rapidly when the sun is overhead (summer, closer to the equator, 11 a.m. to 3 p.m.), and when the skin is less pigmented, but can occur with any skin type. Children with sensitive skin can burn significantly within 15 minutes of midday exposure in summer.

Any child presenting to the ED with sunburn or with a rash in sun-exposed areas may have an underlying photosensitivity disorder. These can be considered in four groups.

Primary photosensitivity disorders.
Inherited disorders including porphyrias.
Diseases with a photosensitive component (systemic lupus erythematosus, dermatomyositis).
Exogenous photosensitivity from drugs or plants.

A high index of suspicion is needed to diagnose photosensitivity. There have been examples of sunburn in children that were attributed to parental neglect but were actually due to a photosensitivity disorder. These diseases are common but diagnostic traps abound. For example, sun-induced rashes may develop in spring with the first sun exposure of untanned skin after winter, but not later in summer. The rash may develop on areas usually covered in winter such as the neck and arms and not on the face. Sun-induced rashes may require a few minutes or several days of sun exposure and may commence days after the exposure. In erythropoietic protoporphyria, sun exposure induces pain without skin changes initially. Viral exanthems may occur exclusively or mainly in areas of sun-exposed skin. Children with solar urticaria develop urticaria on sun-exposed areas.

Management

• Assess for associated causes (below) of increased sun sensitivity. Many children presenting to the ED with ‘sunburn’ have an associated photosensitive trigger. Any child who experiences symptoms within half an hour of sun exposure should be assumed to have an underlying condition.
• Assess the family situation, especially with younger children. Significant sunburn in a young child can occur in the setting of suboptimal child care, although usually it is due to an oversight by otherwise caring parents.
• Within the first few hours of exposure, before blistering has developed, application of topical potent steroid creams can considerably reduce the severity and duration of symptoms.
• Cool compresses and wet dressings will alleviate symptoms. Topical anaesthetics should not be used. Admission and oral analgesia may be required in severe cases. Maintain adequate fluid intake.
• Educate about prevention.

Prevention

Prevention of sunburn is important. Episodes of sunburn are linked to later development of naevi and melanoma.

Parents need to balance the psychological and physical benefits of activities associated with sun exposure (including increased fitness, increased independence, healthier bones and decreased obesity) with the increased risk of skin cancers of all types. In summer, children should minimise sun exposure during the middle 4 hours of the day, wear broad-brimmed hats and long-sleeved shirts in the sun, and use a sunscreen with SPF 30 or greater on exposed parts.

Sunburnt infants regularly present to the ED, partly because of widespread advice that sunscreens are not recommended below the age of 6 months. This recommendation is not based on any evidence of problems in infants. It is based on the premise that it is usually easy to protect young babies who can’t crawl by keeping them out of the sun and appropriately dressed. However, if a young baby is going to be in the sun, sunscreen should be used.

Primary photosensitivity disorders

Polymorphous light eruption (PMLE)

Presents in spring or early summer as skin-coloured or erythematous itchy papules or vesicles on the face, ears, neck or arms. It is recurrent. Recurrences usually occur at the same sites in that child.

Juvenile spring eruption

Is a specific variant of PMLE and is common in 4–12-year-old boys as a recurrent blistering of the ears each spring.

Hydroa vacciniforme

Is rare and can begin at any age in childhood as a sun-induced vesicular eruption on the cheeks during spring and summer. The cheeks, ears, nose, dorsum of the hands and rarely the eyes can be involved. Recurrences occur for many years.

Diagnosis can be difficult and may require formal evaluation in a photobiology unit including assessment of the response to different wavelengths of light. Management requires sun avoidance and often both UVA and UVB sun protection.

Solar urticaria

Presents as urticaria within minutes or hours of exposure and settles within 1 day. Sharp margins are seen at the edges of clothing. Skin chronically exposed to the sun, such as face and hands, is often spared.

Porphyrias and other inherited disorders with photosensitivity

The porphyrias are a group of inherited enzymatic defects in haem synthesis leading to increased levels of porphyrins, some of which cause photosensitivity.

Erythropoietic protoporphyria

Is the most common childhood porphyria. Infants and young children present after brief sun exposure with acute discomfort, burning sensations, itching, erythema, oedema, urticaria and occasionally vesicles, particularly on the face and dorsum of the hands. Episodes are recurrent and with time affected skin appears prematurely aged. Erythrocyte protoporphyrin levels are elevated.

Congenital erythropoietic porphyria

Is rare and presents in early childhood with extreme photosensitivity leading to painful blisters filled with red fluid on the face and dorsum of the hands. Progressive scarring can be severe.

Familial porphyria cutanea tarda

Presents in childhood with chronic blistering on hands, arms and face leading to poorly healing ulcers, atrophic scarring and mottled hypo- and hyper-pigmentation.

If a porphyria is suspected, measure blood, urine and faecal levels of porphyrins. Management requires intensive avoidance of solar radiation including UVA and UVB. β-Carotene is useful in erythropoietic protoporphyria.

Many genodermatoses including xeroderma pigmentosum, Cockayne syndrome, Rothmund-Thomson syndrome and trichothiodystrophies are associated with photosensitivity and increased photo-damage to skin, but do not usually present with blistering.

Photosensitivity and bullous reactions to drugs

Blisters may be the presenting feature of a number of different types of drug reactions. A high index of suspicion is required to diagnose these conditions. Families must be asked about all ingested and topical products including herbal, recreational and prescription drugs and unusual food patterns (e.g. daily cups of celery juice). Families will occasionally not remember the causative drug and deny taking anything, only to recall the vital information days later.

Many medicines can cause increased sun sensitivity leading to erythema, oedema and blistering on sun-exposed areas. Doxycycline (particularly at doses higher than 100 mg day–1), tetracyclines, griseofulvin, isotretinoin, non-steroidal anti-inflammatory drugs, sulfonamides, fluoroquinolones and diuretics are typical causes in children. In one series of children receiving naproxen, 12% developed photosensitivity reactions on the face. Other causes include tars, perfumes, cosmetics, sunscreens, artificial sweeteners and many dyes. As with other photosensitivity syndromes, the rash can occur rapidly or days after the sun exposure and is most prominent on sun-exposed areas. The photosensitivity can persist for up to 3 months after withdrawal of the medication. Prominent hyperpigmentation may persist for months after resolution.

Fixed drug eruptions in children are usually caused by paracetamol, non-steroidal anti-inflammatories or sulfonamides. They are quite common and present as single or multiple, usually circular red patches that may blister. With subsequent exposures, eruptions recur at the same site and sometimes at other sites. Post-inflammatory hyperpigmentation is prominent and may be the only sign of the drug reaction.

Many plants and herbal products contain chemicals that can induce drug reactions including fixed drug reactions, bullous drug reactions and photosensitivity reactions.

Management

• Recognise and stop the causative drug.
• Institute strict sun protection measures. Photosensitivity can persist for 3 months after cessation of the drug.
• If the patient is taking multiple drugs, the timing of the eruption and the frequency of reactions with each of the medications may suggest the causative drug.
• If continued drug ingestion is necessary, reducing the dosage may prevent the reaction.

Photosensitivity reactions to plants

Many plants contain furocoumarins, which are naturally occurring psoralens. UVA light induces covalent bonding of psoralen into DNA, leading to cell death. Typically, a child is playing outside in spring or summer and comes into close contact with a psoralen-containing species (e.g. species of celery, parsley, parsnip, fig, hogweed, limes and other citrus fruits). Several hours later, erythema, oedema and occasionally blistering develop. While contact dermatitis from plants can also present with streaky, often linear vesicular eruptions on areas of contact after exposure, photosensitivity reactions are more often painful, are usually sharply limited to sun exposed areas, and typically heal to leave striking patterns of hyperpigmentation that can persist for months or years.

Management

• Sun protection measures including a UVA sunscreen will prevent phytophotodermatitis.
• Offending plants can be removed.
• Treat as for sunburn.

Contact dermatitis – plants

In children, contact dermatitis reactions from agents other than plants usually do not blister and these conditions are discussed under eczematous rashes (p. 297).

Many plants, including Rhus and Grevillea species, can cause an allergic contact dermatitis. Some species only cause reactions at specific times of the year and contact with the plant at other times does not cause a rash. One to 3 days after exposure, erythema, oedema and vesiculation develop at sites of contact, often in linear distribution. Lesions may persist for 3 weeks. Periorbital erythema and vesiculation is often misdiagnosed in the ED as cellulitis needing antibiotics. Clues to the correct diagnosis are that pruritus is the main symptom, the degree of pain and tenderness is much less than would be expected for cellulitis, systemic features, such as fever, are absent, the outline of the rash often has irregular patterns corresponding to the contact areas and a careful examination will often reveal other lesions on sensitive parts of the body. In particular, genital skin may develop lesions from secondary spread of the allergen via the fingers. Patients with allergic contact dermatitis may be extremely uncomfortable. Treatment often requires a few days of oral prednisolone, topical potent steroid ointments, cool compresses and supportive care. Unlike plant-induced photosensitivity, contact dermatitis from plants does not induce long-term hyperpigmentation.

Irritant contact dermatitis to components of stinging nettles, chilli peppers, mustard, horseradish and other plant products can lead to irritation, stinging, and occasionally blisters. Burning, oedema and blistering in the oral cavity can occur in small children after chewing irritant plants.

Contact dermatitis – id reactions

Repeated exposure to an allergen can result in a papulovesicular eruption at sites distant from the area of contact. This is thought to be a result of systematised contact sensitisation. The id reaction may be local or generalised. Examples include non-infective blisters erupting on the hands of a child with chronic tinea infection of the feet, and a severe generalised itchy vesicular rash on an adolescent using topical neomycin ointment.

Isolated blisters

For a child who presents with a single blister or a few blisters as an isolated finding, consider:

• Mastocytoma. Usually in an infant with a history of recurrent blistering or crusting at the site of a brownish macule, often misdiagnosed as recurrent localised impetigo. There may be one brownish lesion or as many as hundreds.
• Insect bite. There may be a few lesions in one area. Non-blistered papules may have a tiny central red bite punctum.
• Irritant contact dermatitis.
• Spider bite. These can grow over days to become a non-tender blister with a diameter of many centimetres. They are uncommon. Regular dressings may be required. Debridement is rarely necessary. White-tailed spiders and huntsman spiders do not cause chronic necrotic ulcers.
• Scalds or burns from cigarettes or other hot objects. Look for characteristic patterns in the burn, as well as other factors on the history or examination suggestive of non-accidental injury or suboptimal caring practices.
• Fixed drug eruptions, e.g. from tetracyclines, sulfonamides, non-steroidal anti-inflammatory drugs or paracetamol.
• Friction. If minor friction appears to cause more blistering than expected on hands and/or feet in children, consider the possibility of a mild inherited blistering disorder (e.g. mild epidermolysis bullosa simplex). There may be a positive family history of childhood blistering that settled in later life.
• Artefactual lesions caused by either the child or a carer.
• Bullous Sweet syndrome or pyoderma gangrenosum.

Chronic erosions or ulcers

Several primary skin conditions can cause chronic erosions or ulcers in children, including itchy conditions such as scabies and papular urticaria. Also consider:

• Immunodeficiencies. Recurrent boils can be seen in chronic granulomatous disease and hyper IgE syndrome. Poor wound healing is a feature of leucocyte adhesion defects.
• Skin fragility syndromes. In junctional and dystrophic forms of epidermolysis bullosa, chronic ulcers related to minimal skin trauma may be seen in association with failure to thrive, anaemia and gastrointestinal tract involvement.
• Porphyria. Several enzyme defects in haem metabolism are associated with chronic erosive lesions, photosensitivity and hyperpigmentation. Episodes of acute pain or neurological dysfunction are rarely seen in childhood porphyrias.
• Artefactual lesions caused by either the child or a carer.
• Pyoderma gangrenosum.
• Mycobacterium ulcerans infection.

Neonatal vesicles

A neonate with vesicles or blisters requires urgent assessment, as potential causes include infection with herpes simplex virus, varicella zoster virus and Staphylococcus aureus, including bullous impetigo. Neonates who acquire herpes simplex virus at birth usually present at a few days of age with grouped vesicles, often on the scalp. Lesions may rapidly spread and coalesce. Collect epithelial cells from the base and roof of a vesicle for immunofluorescence and viral culture. This is not ‘just a swab’ and it requires some persistence to collect enough cells. CSF must be examined for herpes simplex virus DNA, as 30% of neonates with apparently localised skin disease also have CNS involvement. Empiric intravenous aciclovir is essential until herpes infection has been excluded.

Non-infective causes of neonatal vesicles include:

• Epidermolysis bullosa. Over 40 inherited diseases are associated with skin fragility. Presentation ranges from a few isolated blisters in otherwise well children to extensive blistering at any site of handling, with associated systemic problems.
• Miliaria. Very superficial blistering in hot or occluded areas.
• Ichthyosis. Bullous subtypes present as blisters or erosions on red skin, which gradually becomes more scaly.
• Langerhans cell histiocytosis – vesicles and/or purpuric crusted lesions (see p. 294).
• Incontinentia pigmenti. This disease is X-linked and fatal in male fetuses. Girls present with lesions distributed in linear patterns. Lesions evolve through vesicular and warty phases to eventually leave permanent hyperpigmented streaks. Seizures and developmental, ocular and dental problems may occur.
• Mastocytosis. Urtication and blistering occur spontaneously or on top of oval brown macules.

Pustular rashes

Consider acne, folliculitis, drug reactions, pustular psoriasis, scabies, perioral dermatitis, tinea and localised bacterial infection. All vesicular rashes can become pustular if the vesicles persist for more than a couple of days. Vesicles on areas of thick skin can be white and look like pustules, e.g. on the toes in hand, foot and mouth disease. If in doubt, prick one lesion to reveal the clear fluid within.

Acne

Acne mainly affects the forehead and face but can involve other sebaceous gland areas (neck, shoulders and upper trunk). Early lesions include blackheads, whiteheads and papules. In more severe cases there may be pustules or inflammatory cysts that can lead to permanent scarring. Acne is common in adolescence. It is treatable and no person with acne should be told it is an inevitable part of adolescence. Several topical and oral acne therapies are available and should be used to treat the disease. Under-treated acne is a major medical cause of significant morbidity in adolescents and has a recognised mortality as a factor in teenage suicide. It can also lead to permanent scarring in 10% of untreated cases (Fig. 12.1.6). Significant acne in an adolescent attending the ED for another reason should not be ignored. The adolescent should be offered information, initial treatment and referral for ongoing management.

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Fig. 12.1.6 Cystic acne. Acne should be treated with isotretinoin before reaching this stage.

Management

• Most cases are mild and either require no intervention or can be managed with topical treatments. A first-line topical treatment is benzoyl peroxide 2.5% applied once or twice a day. Warn the adolescent that improvement with topical therapy occurs steadily over 1–4 months (not in a few days). Other topical agents include topical antibiotics for inflammatory lesions (clindamycin, erythromycin or tetracycline), topical retinoids (isotretinoin, adapalene) or azelaic acid. These can be used singly or in combination and combination preparations are becoming more available. All of these topical agents have the potential to cause irritation.
• If there are prominent red papules or pustules, a course of oral antibiotics for 3–6 months in combination with a topical treatment is warranted (e.g. tetracycline 500 mg twice daily, erythromycin 500 mg twice daily, doxycycline 50–200 mg day–1). Oral hormone therapy can help female patients.
• If the acne is severe, or if antibiotics and topical treatment have not resulted in considerable improvement in 3 months, oral isotretinoin (Roaccutane) is indicated. Prescription of isotretinoin is tightly controlled because it is expensive and because it is teratogenic, requiring absolute avoidance of any pregnancy risk in girls. In boys, and in girls who do not become pregnant, it is safe and highly effective. Most adolescents with troublesome acne can be cured with oral isotretinoin.
• Some acne sufferers develop scarring. This can be quite subtle and can occur with otherwise fairly mild disease. Any scarring is an indication for oral antibiotics and early consideration of oral isotretinoin. Similarly, the presence of any cysts should alert you to the likelihood of scarring and the need for oral therapy.

Acne and depression

Both adolescence and acne can be associated with depression. Significant depression is an indication to consider oral isotretinoin therapy. For several years, the issue of whether isotretinoin can trigger depression and suicide has been investigated. Current medical evidence suggests that treatment of severe acne with oral isotretinoin may decrease the risk of suicide. Assessment and treatment of any depression is required.

Acne fulminans

Acne fulminans typically occurs in young males being treated for acne. There is sudden onset of fever, malaise, arthralgia, myalgia, lymphadenopathy and/or hepatosplenomegaly in association with a rapid worsening of acne over the trunk and shoulders. Many painful cystic lesions develop and become haemorrhagic and ulcerated. Many laboratory abnormalities have been noted, including elevations of white cell count, erythrocyte sedimentation rate, C-reactive protein and liver enzymes. The cause is unknown but may be an abnormal immunological response rather than a primary bacterial infection. The response to oral antibiotics is slow and indeed these adolescents are often taking oral antibiotics at the time of onset.

Management

• Oral prednisolone 0.5–1 mg kg–1 daily for 4–6 weeks (thereafter slowly reduced to zero).
• Oral isotretinoin being added to the regimen at the fourth week, initially at 0.5 mg kg–1 daily and gradually increased to achieve complete clearance.

Acne with Gram-negative folliculitis

This can develop in patients treated for acne with long-term antibiotics. It is more common in adolescents with an oily complexion. It presents as rapidly worsening acne with pustular lesions on the face. Several common Gram-negative pathogens may be involved. Treat with oral trimethoprim and oral isotretinoin.

Early onset acne

Acne normally appears after the onset of pubertal changes such as testicular enlargement, pubic hair and breast development. However, comedonal and occasionally papular lesions may be the first manifestations of puberty in a child. These changes can begin up to 2 years before other signs of puberty. Early onset of comedonal lesions, even if mild, is associated with more severe acne several years later.

If comedones or acneiform papules are noted before puberty (see Fig. 12.1.1), you should consider the possibility of pathological androgen secretion (see below). Look for increased growth, genital development and advanced radiological bone age.

Atypical acneiform rashes

Acne that is atypical in age of onset, distribution, morphology or severity may be associated with systemic disease. Consider:

• Glucocorticoid excess, either exogenous or endogenous. This can give a monomorphic acneiform rash on the face and trunk. Other cushingoid stigmata may be present. In children on corticosteroid treatment, the rash may appear as the dose of corticosteroid is being weaned. Glucocorticoid acne may be due to Malassezia folliculitis. If there is no response to tetracycline, treatment of Malassezia folliculitis with topical or oral antifungals may be required (see Folliculitis below).
• Androgen excess. Other features depend on the age and sex of the child. In younger children accelerated growth, body odour, pubic hair, clitoromegaly (but not breast development) and penile (but not testicular) enlargement may be present. In teenage females, polycystic ovary syndrome is commonly the cause. Other causes include late-onset congenital adrenal hyperplasia, and virilising tumours. Investigations may include X-rays for bone age, pelvic ultrasound, plasma androgens, fasting glucose and insulin, and response to dexamethasone suppression.
• Precocious puberty.
• Several drugs can induce an acneiform rash with monomorphic papules and pustules in post-pubertal children. The distribution is different from acne vulgaris, often involving arms, legs or trunk, and comedones are not present. Affected individuals often have a history of troublesome acne vulgaris. Possible causative agents include anti-epileptic medications, especially phenytoin and phenobarbital, glucocorticoids, testosterone, isoniazid, lithium and iodides.
• Apert’s syndrome and related craniofacial syndromes can present with more severe widespread acne.

Folliculitis

Infection of the hair follicles is usually due to Staphylococcus aureus. Predisposing factors include a moist environment, a heavy bacterial load (e.g. adjacent to wounds or anal region) and excessive occlusive ointment, particularly on the trunk. Treatment involves avoidance of the predisposing factors, use of topical cleansers such as chlorhexidine and, rarely, oral antibiotics. Folliculitis often occurs repeatedly over a period of months and may require continued topical measures for 3–6 months. In resistant cases, daily use of topical benzoyl peroxide lotion may be helpful.

Folliculitis can occur in a child with moderate or severe eczema. Oral antibiotics are usually beneficial in this setting.

In adolescents, Malassezia folliculitis is common and presents as a persistent itchy rash with many tiny monomorphic erythematous papules and pustules on the back, shoulders and upper trunk. It is often associated with occlusion or sweating. Daily application of ketoconazole 2% shampoo is effective in gaining control. For resistant cases, use oral ketoconazole 400 mg weekly for 6 weeks taken with a glass of grapefruit juice followed by indefinite weekly shampooing with selenium sulfide 2% shampoo.

Occasionally, pruritic papules and pustules can develop many hours after soaking in a hot spa. Lesions usually occur under the bathing costume and are caused by Pseudomonas aeruginosa. Oral antibiotics are not usually needed.

Acute generalised exanthematous pustulosis (AGEP)

AGEP appears as a rapidly developing facial or truncal erythema with hundreds of tiny sterile pustules. Oedema is often seen in the affected areas. Fever and malaise may be present. Healing is associated with extensive superficial peeling. In some cases, children presenting with acute generalised exanthematous pustulosis have an underlying psoriatic tendency.

Many common medications, including amoxicillin, erythromycin, azithromycin, sulfonamides, anticonvulsants (especially carbamazepine) and non-steroidal antiinflammatory drugs can cause this. Acute generalised exanthematous pustulosis drug reactions often begin within hours of commencing the drug. Other causes include Group A streptococcal infection.

Treat by stopping any offending medication. Give oral antibiotics for underlying streptococcal infection if required.

Pustular psoriasis

Psoriasis can present with pustules on an erythematous background. The pustules are sterile. The affected area may be limited to fingers, palms and soles, or local areas of skin, often with an annular arrangement of pustules. Alternatively, there may be erythroderma, high fever, malaise and arthralgias with widespread pustules coalescing into sheets of pus. Local pustular psoriasis can be treated topically (see psoriasis, p. 295). Generalised pustular psoriasis requires admission to hospital, rest, skin emollients and/or wet dressings, monitoring of fluid balance, electrolytes, renal and cardiac function and oral therapy (see erythroderma p. 281 and psoriasis p. 295).

Neonatal pustules

In the neonatal period, pustules may be part of several transient benign conditions. Pustules or vesicles may also be a marker of serious underlying illness, even in the absence of fever and lethargy. Consider:

• Infection, either congenital or acquired, e.g. Staphylococcus species, Group B streptococci, Haemophilus influenzae, Candida species.
• Neutropenia from any cause. Superficial bacterial pustules may be the only sign of congenital neutropenia.
• Toxic erythema of the newborn. In this benign condition, well term babies develop many tiny papules or pustules on an erythematous macular background in the first few days of life. Lesions clear within several days.
• Transient neonatal pustular dermatosis. Loose pustules are present from birth, and disappear within two days. This condition is more common in dark-skinned babies.
• Acropustulosis of infancy. Itchy vesicles and pustules appear on the hands and feet, usually commencing in the first couple of months of life and continuing for some months. New crops appear each 2–4 weeks. Sleep disturbance is common. In some infants; it appears to follow previously treated scabies infection. Pustules contain neutrophils and are sterile. Multiple scrapings may be necessary to exclude active scabies infection. Potent topical steroids assist control of flares, and the condition remits over 1–2 years.
• Eosinophilic pustular folliculitis (scalp). Yellowish pustules appear on the scalp and face within the first days of life. Lesions crust over and new lesions develop for some weeks. Pustules contain eosinophils and are sterile but secondary infection can occur. Mid-potency topical corticosteroids are helpful to control itch.
• Milia (white papules on the face) and sebaceous hyperplasia (yellowish papules, particularly around the nose) can be misinterpreted as pustules. Both resolve within a few weeks of birth.
• Neonates with Down’s syndrome can develop a leukemoid pustular reaction which is self-limiting.

Neonatal pityrosporum folliculitis

This extremely common eruption is referred to as ‘milk spots’, the ‘6-week eruption’ or ‘infantile acne’. It presents as a widespread papulopustular follicular eruption on the face and torso. This is not true acne and comedones are not present. It is due to an inflammatory reaction to Pityrosporum yeast as the newborn sebaceous glands, activated during pregnancy, are returning to their quiescent childhood state. It is self-limiting and often needs no treatment. In more severe cases, application of ketoconazole 0.2% solution (dilute the 2% shampoo) by cotton bud to affected areas twice daily leads to rapid clearing.

Papular (raised) rashes

If a child has itchy papules, consider scabies, urticaria, serum sickness, papular urticaria, molluscum, Malassezia folliculitis, dermatitis herpetiformis or Langerhans cell histiocytosis. If papules are not itchy, consider urticaria, molluscum, warts, acne, skin appendageal tumours, melanocytic naevi, Spitz naevi, pilomatricomas, keratosis pilaris, vasculitis and papular acrodermatitis. For raised red circles or rings, consider urticaria. For softer red, purple or blue swellings, consider haemangiomas or vascular malformations. For haemorrhagic papules, consider Henoch–Schönlein purpura and other causes of vasculitis. If papules are yellowish when blanched, consider juvenile xanthogranulomas or xanthomas.

Papules or nodules may also occur in a number of disorders including acute rheumatic fever, juvenile chronic arthritis, systemic lupus erythematosus and neurofibromatosis, but are rarely the presenting feature.

Scabies

Scabies infection occurs as a result of close, usually repeated, contact with an infected individual. Scabies mites eat into the upper skin forming burrows a few millimetres in length around the fingers, palms, wrists, elbows, axillae, nipples, penis, and soles. Early burrows may be vesicular. Usually only a few mites are present.

An intensely itchy secondary papular eruption develops 2–6 weeks after first exposure to the Sarcoptes scabiei mite or 1–4 days after subsequent reinfestation. This secondary eruption represents an immune response to the scabies antigen and does not mean that mites are spreading all over the body. Papules can occur anywhere, including the palms, soles, axillae and genitalia, but are most prominent on the abdomen, buttocks and thighs. The scalp and head may be involved in infants and young toddlers. Inflammatory nodules may also develop, especially on covered areas. Excoriations and secondary impetigo may be present. Scabies is pandemic and affects both adults and children.

Not all itchy parasitic rashes are scabies. Many species of parasite can cause small itchy papules on the skin, in some cases hundreds of lesions. Bird mites, fleas, body lice, mosquitoes, sand flies, horse flies, bed bugs, ticks, chiggers, midges and harvest mites can all masquerade as scabies. Parasites can be collected from the skin on transparent adhesive tape. The CSIRO Australian National Insect Collection provides an identification service on http://www.csiro.au/services/InsectID.html.

Management

• Treatment of scabies is expensive and upsetting. If there is any doubt about the diagnosis, confirm by scraping to find a scabies mite, or refer before treating.
• Permethrin 5% cream.
• An alternative, recommended for pregnant or neonatal cases, is sulfur 6% in yellow soft paraffin. This is unpleasant and has no proven safety advantages over permethrin in these groups. The following are not recommended: lindane 1% (contraindicated in infants or women who are pregnant or breast-feeding) or benzyl benzoate 25% (too irritant for children and ineffective if diluted).
• Apply to dry skin (not after a bath) from the neck down to all skin surfaces. For infants, apply to the scalp as well (not face). Use mittens if necessary to prevent finger-sucking.
• Leave the cream on for at least 8 hours.
• Wash the cream off. Wash clothing, pyjamas and bed linen at this time.
• Remove soft toys from the bed. The scabies mite cannot live for long periods away from the body, and insecticide sprays and cleaning of furniture and carpets are not warranted.
• Exclude from school until after treatment has commenced.
• Treat all family members and any other people who have regular close skin contact with the affected individuals.
• The itch takes a week or two to settle and can be treated with topical or oral corticosteroid. Nodules may take months to resolve despite successful treatment of the scabies infestation.
• Reinfestation is common. To minimise the risk of reinfestation, the family should notify all social contacts (e.g. crèche, school or close friends) to ensure that all those infected receive treatment.
• Treat secondary impetigo with oral cefalexin 30 mg kg−1 (max 500 mg) three times daily.
• Post-streptococcal glomerulonephritis may be seen after chronic impetigo secondary to scabies in the indigenous population. Oedema, hypertension and haematuria may occur over the next 2 months. In a child with long-standing infected scabies where ongoing care may be suboptimal, review and urinalysis to monitor for renal involvement is warranted. Examination of the child and siblings for signs of rheumatic heart disease is also warranted in this patient population.

Papular acrodermatitis of childhood

Papular acrodermatitis of childhood usually occurs in children aged 1–3 years but can occur outside this range. It is a reaction pattern to many infectious agents, including coxsackie viruses, echoviruses, Mycoplasma species, Epstein–Barr virus, adenovirus, respiratory syncytial virus, rotavirus, cytomegalovirus, hepatitis B virus and others. It has also been reported after all standard childhood vaccines. It is common and a regular source of confusion in EDs.

Papular acrodermatitis of childhood is characterised by the acute onset of monomorphic, red or skin-coloured papules mainly on the limbs, buttocks and face, with striking sparing of the trunk (Fig. 12.1.7). In any given patient, the papules tend to all look the same, typically firm and dome shaped, measuring 2–4 mm in diameter. However, in different patients, the papules can vary from tiny, skin-coloured papules to larger urticarial plaques. Lesions may coalesce into patches on the extensor surfaces of the elbows and knees. Lesions may be papulovesicular (particularly on the limbs) or purpuric (particularly on the face). Hundreds of lesions may appear over several days. It is usually asymptomatic but may be itchy. Complete resolution occurs in 4–8 weeks.

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Fig. 12.1.7 Papular acrodermatitis of childhood showing almost complete sparing of the trunk.

Affected children may be otherwise well or may have features of the underlying infection, such as mild fever, malaise, coryza, sore throat, lymphadenopathy and splenomegaly. Lymphopenia or lymphocytosis may be present. In some cases, no history of a preceding or intercurrent illness can be found.

Papular acrodermatitis of childhood was formerly known as Gianotti–Crosti syndrome and was initially described as a manifestation of hepatitis B infection in Italy. This association has not been shown to be of general relevance, and papular acrodermatitis of childhood has been recognised as benign and much more common than previously thought.

Management

• Reassure and advise that clearing can take a few weeks.
• Children with papular acrodermatitis of childhood do not routinely require investigation to determine the underlying cause.
• Itch may require topical mid-potency corticosteroids and/or oral antihistamine.
• No exclusion from school or crèche is needed.

Papular urticaria

This is a clinical hypersensitivity to insect bites and may occur in just one child within a household, even though all family members may be bitten. New bites appear as crops of asymmetrical, small, red papules, usually in warmer weather. Older bites appear as 1–5 mm papules, sometimes with surface scale or crust, or with surrounding urticaria. Vesicles or pustules may form in the centre of lesions. Individual lesions may resolve in a week or, if scratched, may last for months and may repeatedly flare up after fresh bites elsewhere. Itch is often intense and secondary ulceration or infection can occur. Full resolution usually occurs within 9 months. However, scratching can lead to secondary changes, with non-healing erosions, ulceration, scarring and nodule formation. These lesions remain itchy and a cycle of scratching and skin destruction can persist for years or decades if not treated. Improvements occur with new treatments but relapses are common without considerable medical support.

Management

• If the diagnosis is unclear, skin biopsy is useful as the typical histological findings are specific for insect-bite reactions.
• Prevent bites, e.g. by adequate clothing, modifying behaviour that leads to exposure, occasional use of repellent, and the treatment of pets and house for fleas and mites if necessary. The commonest source of bites is from mites in roof-dwelling animals such as birds, rats and possums. Surface spray of ceiling vents can be very useful.
• Treat the itch with an agent such as aluminium sulfate 20% (Stingose), liquor picis carbonis 2% in calamine lotion, potent steroid ointment or antihistamines.
• Protective dressings (e.g. Duoderm) can speed the healing of lesions. In older children, intralesional injection of corticosteroid is effective.
• Treat secondary infection with topical mupirocin ointment 2% or oral cefalexin 30 mg kg−1 (max 500 mg) three times daily.
• For more persistent and severe lesions, an intensive regimen may be necessary, including inpatient admission for moisturiser, potent topical steroid ointment and wet dressings, combined with continued intensive care of any relapse for weeks or months. Treatment needs to be modified according to response.

Molluscum

Molluscum is caused by a pox virus and is very common. Most children get at least a few molluscum at some stage between the ages of 1 and 12 years. Uncomplicated molluscum lesions are easily recognised as firm, pearly, 1–4 mm dome-shaped papules with central umbilication. They are sometimes misdiagnosed as vesicles on initial examination. A child may develop a few or a great many lesions and individual lesions may last for months. Lesions can come and go for up to 3 years without causing any problems in most children. Complete resolution will not happen until an immune response develops, which may take from 3 months to 3 years.

Rarely, individual lesions can grow to over 1 cm in diameter. Individual lesions can become inflamed and, uncommonly, can develop secondary abscesses. More commonly, presentation to the ED is triggered by the development of widespread itchy and excoriated eczematous lesions in surrounding skin, usually on the lateral chest and axillary region or between the thighs. In such cases, recognition can be difficult, as the secondary changes can obliterate the primary lesions. A carefully taken history of the initial lesions is usually diagnostic.

Molluscum is common in the anogenital area and occurrence at this site does not suggest child sexual abuse. Molluscum is common on the face and occurrence at this site does not suggest underlying undiagnosed immunodeficiency.

Molluscum may occur on the eyelid margin or adjacent area. This can cause a persistent unilateral conjunctivitis. The molluscum may be isolated and subtle and go unnoticed for months during which the child may receive multiple courses of antibiotic treatment for conjunctivitis (Fig. 12.1.8).

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Fig. 12.1.8 This 6-year-old boy had presented to the ED four times in 6 months with recurrent unilateral conjunctivitis. Molluscum can be seen on the surrounding skin and a small papule towards the lateral end of his lower lid margin is also a molluscum. Treatment of the molluscum cured the conjunctivitis.

Management

• Most children with molluscum require no treatment.
• Children with molluscum should not share towels but should not be restricted in their activities. Swimming should not generally be restricted. It is possible that spread to other parts of the body and to other children may be reduced by advising the child not to soak in warm water (baths, spas, heated pools). This is a significant restriction for many children with long-term sequelae if they miss their school swimming lessons. If restrictions are imposed on the child, lesions must be actively treated to ensure rapid clearing.
• Any child having problems with molluscum should be treated.
• The treatment depends on the age of the child, the location of the lesions and any secondary changes. Uncomplicated lesions not causing problems and not spreading can be left alone.
• If the presenting problem is the itch from secondary eczema, treatment of the eczema with mild or mid-potency topical steroid ointment may be all that is required. Try not to overuse as it is possible that this may encourage spreading of molluscum lesions.
• It is not difficult to destroy molluscum lesions. Simply deroofing the central umbilication is almost painless and leads to the papule becoming inflamed and resolving. In older children, this can be achieved with superficial needle pricking or light cryotherapy. Benzoyl peroxide 5%, a variety of chemical irritants and tape stripping can all be used but these can tend to flare any surrounding eczema.
• Topical cantharidin (e.g. Cantharone) is the most rapid and effective way of dealing with molluscum in many situations. This is painless on application and causes small blisters at the site over the next several hours. Importation of cantharidin requires a personal TGA permit and is not warranted unless you see many children with troublesome molluscum.
• Imiquimod 5% cream nocte for several days is expensive but may be useful for small numbers of lesions at difficult-to-treat sites.
• Several treatment options exist for molluscum around the eye and causing conjunctivitis. One or two lesions in older non-anxious children can be treated physically as for elsewhere on the face. Imiquimod 5% cream can be tried. If there are many lesions elsewhere, treating all the other lesions away from the eyes often induces rapid resolution of the eye lesions as well. In anxious children with significant problems with conjunctivitis, sedation or a brief general anaesthetic may be warranted.
• Inflamed lesions rarely warrant antibiotic treatment or drainage.

Adnexal tumours – pilomatricoma

Many different benign tumours of the various cell types in hair follicles, sebaceous glands and sweat glands can present as papules during childhood. The most common by far are pilomatricomas. These present at any age in childhood as a slow-growing papule on the head, face or neck (or occasionally elsewhere) that can be 4–40 mm in size. They may be skin-coloured, white or bluish and are usually firm or hard, often due to calcification within the lesion. They may be lobulated. The main differential is an epidermal cyst. An ultrasound may confirm the diagnosis by demonstrating calcium shadows, which are not present in epidermal cysts. Pilomatricomas do not usually regress. Surgical removal is usually recommended because of the appearance but is not urgent.

Keratosis pilaris

This is a rough, somewhat spiky papular rash, mainly on the upper outer arms, thighs and/or cheeks with variable erythema. It affects 50–80% of all adolescents and approximately 40% of adults. About 30–50% of patients have a positive family history. Autosomal dominant inheritance with variable penetrance has been described. It appears in infancy and persists throughout life. However, it tends to improve towards adulthood. Rarely, the erythema and papules are florid and distressing and treatment is warranted.

Management

Reassure the patient that this is rarely a problem. Soap avoidance and moisturisers can improve the spiky feeling. Most children need no further treatment. Steroids do not help.

Granuloma annulare

Granuloma annulare is not common in children. It begins as a small skin-coloured or red papule that spreads outward over many weeks or months to give an annular, asymptomatic ring, usually on the hands or feet. Although often misdiagnosed as tinea, the epidermis is not scaly and discrete subcutaneous papules can be felt all around the ring. It is slow growing and takes months to reach a size of 2 cm. Resolution usually occurs within a year or two. No investigation is necessary. Most children should be reassured and don’t need treatment.

Langerhans cell histiocytosis

Langerhans cell histiocytosis may present in several ways and should be considered as a possible diagnosis in any unusual, non-healing rash in infancy.

In neonates, Langerhans cell histiocytosis may present as a congenital self-healing form. One or a few papules are present at birth or shortly thereafter. They can be many millimetres in diameter and classically have a raised border and central necrosis. The papules usually show complete regression within months. Recurrence years later with visceral involvement or disseminated disease has been reported, and long-term monitoring is warranted.

In infants, Langerhans cell histiocytosis can present as recalcitrant ‘cradle cap’ with scaly, papular and petechial scalp lesions, often mistaken initially for severe seborrhoeic dermatitis. Flexural areas, especially the groin and anogenital area, can be involved, presenting as a chronic weeping ‘nappy rash’. The presence of papules and/or petechiae, sometimes with ulceration, and the lack of response to treatment for napkin dermatitis should raise suspicion.

In infants and older children, there may be widespread, often itchy, small haemorrhagic papules mimicking a vasculitis. Erythematous and purpuric scaling and papules may be present on the hands and feet, and nails may become dystrophic. Mucosal involvement can lead to ulceration on the gums or palate.

Extracutaneous disease can involve the liver, lymph nodes, marrow, bone and CNS. Diabetes insipidus can occur.

Management

• Confirm the diagnosis with a skin biopsy.
• Investigate for other organ involvement with skull, chest and skeletal X-rays, dental examination, full blood examination and liver function tests.
• Skin lesions can be treated with topical corticosteroid application.
• While Langerhans cell histiocytosis can be self limited; it can also be rapidly progressive with progressive organ involvement and a poor prognosis, requiring intensive chemotherapy.

Juvenile xanthogranulomas

Juvenile xanthogranulomas are the commonest cause of yellow papules in children. Occurring in early childhood, lesions appear as low, dome-shaped papules 2–5 mm in diameter. They may be yellow or red-brown lesions that become yellow when blanched. They are often on the scalp but can occur elsewhere. There may be one or multiple papules appearing over weeks or months. Biopsy may be required to confirm the diagnosis. Resolution without treatment usually occurs within a few years. Juvenile xanthogranulomas are not associated with lipid disorders.

Children with neurofibromatosis have a considerably increased chance of having juvenile xanthogranulomas. The known increased risk of myelomonocytic leukaemia in a child with neurofibromatosis is probably not changed significantly if juvenile xanthogranulomas are also present, despite statements to the contrary in many texts.

Children less than 2 years old with multiple juvenile xanthogranulomas should have an ophthalmology assessment. Ocular juvenile xanthogranulomas leading to glaucoma have been reported in this subgroup of patients.

Xanthomas

True xanthomatous papules associated with elevated cholesterol levels are rare in childhood. They may present as multiple eruptive xanthomas, tuberous xanthomas (usually distributed over the elbows, knuckles, buttocks, knees and heels) and tendinous xanthomas (usually on tendons around the elbow, wrist, hand, or ankle). Investigation to exclude hyperlipidaemias is mandatory. Consider:

• Primary hyperlipoproteinaemias. Skin lesions may present between 5 and 15 years of age, sometimes as tendinitis or tenosynovitis. Look for signs of atherosclerotic disease, and a family history of high cholesterol, early myocardial infarcts or strokes.
• Secondary hypercholesterolaemia. This can occur in hypothyroidism, biliary cirrhosis, diabetes mellitus, glycogen storage disease and nephrotic syndrome.

Angiofibromas in tuberosclerosis

Facial angiofibromas may be the first sign of tuberosclerosis. They appear as small, red-brown papules (not pustules) on the cheeks from about 5–6 years of age and can be misinterpreted as flat warts or early-onset acne.

Red scaly rashes

Redness and scale indicate a combination of vasodilatation and epidermal involvement. Atopic eczema is the commonest cause of red scaly rashes in children (see p. 297). Other red scaly eruptions include seborrhoeic dermatitis (infants), psoriasis, tinea corporis, pityriasis rosea and pityriasis versicolor. If itch is present, consider any of the causes of eczematous rashes (p. 297).

Psoriasis

Psoriasis can occur at any age. Every year in a city of 2 million people, 400 children will present with psoriasis for the first time. Lesions typically begin as small, red papules that develop into circular, sometimes itchy, sharply demarcated, erythematous plaques with prominent silvery scale. However, psoriasis can present in many ways, including isolated thick scaly scalp lesions, scaly plaques on the hairline and behind the ears, annular lesions, pustular lesions, palmoplantar psoriasis, guttate psoriasis and flexural psoriasis. Therefore, psoriasis must be considered in the differential diagnosis of any red, scaly rash, particularly if well-demarcated and not particularly itchy.

Guttate psoriasis describes the eruption of hundreds of small, scaly papules on the trunk and limbs, often following a streptococcal throat infection.

Flexural psoriasis can involve any of the skin folds, particularly the anogenital area, and is more common in children than in adults. Psoriasis at flexural sites presents as moist, non-scaly erythema, often painless but sometimes with secondary fissuring or streptococcal infection.

Minor nail pitting is often seen in childhood psoriasis.

Management

• Presentation to the ED is often precipitated by the onset of guttate psoriasis or by secondary problems with long-standing anogenital psoriasis. The treatment depends on the site and extent of disease and the age of the child. Guttate psoriasis is often most easily managed with an extemporaneous tar cream, e.g. liquor picis carbonis (LPC) 3% and salicylic acid 2% in Sorbolene cream, 500 g. Adolescents are less tolerant of tar creams.
• Minimise skin trauma. Use regular moisturiser.
• Treat isolated skin plaques with either topical steroids (e.g. mometasone) or topical calcipotriol, or both, for 4 weeks, with clinical monitoring. Topical steroids are not used for large areas in childhood psoriasis because of the possible development of rebound pustular disease. Thick scalp plaques can be softened overnight with a tar cream and removed with a tar shampoo. Generally avoid tar cream on the face, flexures and genitalia as it can be irritating.
• Use hydrocortisone 1% or pimecrolimus 1% cream on the face, flexures and anogenital region.
• Palmoplantar psoriasis can be resistant to treatment. Initially treat with topical potent corticosteroid and calcipotriol ointment.
• Secondary infection including perianal streptococcal infection may require treatment with oral penicillin. Recurrent or persistent streptococcal infection or carriage should be considered but is uncommon.
• A mild normocytic (occasionally microcytic) anaemia of chronic disease can occur in more severe cases.
• Appropriate medical follow up is essential. Psoriasis will recur. Widespread or resistant psoriasis may need treatment with one or more of dithranol, ultraviolet therapy, acitretin, methotrexate or ciclosporin, all of which are effective.
• Widespread involvement may lead to erythroderma with metabolic and other complications (see erythroderma, p. 281).

Tinea corporis

Tinea corporis (often called ringworm) is a common skin disorder, especially among children, but it may occur in people of all ages. It is caused by mould-like fungi (dermatophytes). Tinea infections can be transmitted by direct contact with affected individuals or by contact with contaminated items such as combs, clothing, shower, or pool surfaces. They can also be transmitted by contact with pets that carry the fungus (cats are common carriers). The typical lesion is a slow-growing erythematous ring with a clear or scaly centre. Scale is usually most prominent on the outside of the annular ring. However, tinea corporis can present in a wide variety of ways. It can be pustular or vesicular, particularly on the soles (Fig. 12.1.9), or it can spread to many sites within days. Between the toes, it presents as an itchy, white, scaly and macerated rash. Previous treatment with steroid ointments often leads to partial improvement in symptoms but causes spreading of the rash, the development of papules and the masking of diagnostic features. Tinea should be considered in any red, scaly rash where the diagnosis is unclear, particularly if there is a gradually spreading eruption with inflammatory edges.

image image

Fig. 12.1.9 Inflammatory bullous fungal infection. (A) The foot with (B) secondary id reaction involving the hands.

Management

• Confirm the diagnosis by scraping the scale for microscopy and culture.
• The family should identify and treat the source animal if any.
• Treat focal lesions with terbinafine cream (twice daily for 1 week) or an imidazole cream (e.g. clotrimazole, miconazole or econazole two to four times daily for 4 weeks).
• Rapidly spreading or widespread lesions, or involvement of hair-bearing areas usually requires oral griseofulvin (20 mg kg–1 day–1 in divided doses).
• Combined steroid and antifungal ointments (e.g. Kenacomb) are often ineffective for clearing tinea corporis.
• Exclude from school until 1 day after treatment has commenced.

Pityriasis rosea

Pityriasis rosea is common from 1–10 years. The cause is uncertain, but is thought to be viral. Human herpesvirus types 6 and 7 (HHV-6, HHV-7) have been implicated. A similar eruption may occur in response to a number of drugs. A pink scaly patch 2–4 cm in diameter near the shoulders or hips (herald patch) is the first sign in about 50% of children and is often misdiagnosed as tinea corporis because of its central clearing. However, unlike tinea, the scale is usually most prominent on the inside edge of the inflammatory ring. A few days or weeks later (or as the first feature if no herald patch is present), many pink/red, scaly, oval macules appear, mainly on the trunk, arms and thighs. The face, palms, lower legs and soles are largely spared. There may be thin scale within the lesions and oval lesions may align with skin lines to give a ‘Christmas tree’ pattern on the back and trunk. Pityriasis rosea usually persists for 1–2 months. It may be mildly itchy but is often asymptomatic.

Pityriasis rosea may be atypical. Lesions may be papular, crusted, vesicular or purpuric. The distribution may involve neck and extremities.

Secondary syphilis can appear in a similar fashion, but mucosal and acral lesions are usually present. Secondary syphilis should be excluded in any adolescent at risk of sexually transmitted disease who presents with pityriasis rosea, particularly if palms and soles are involved.

Management

• Reassure the patient.
• Sunlight (or ultraviolet light in troublesome cases) will hasten clearing. Topical corticosteroids do not help. Emollients, or occasionally oral antihistamine, are useful for itch.
• In an adolescent at risk for sexually transmitted diseases, arrange VDRL test.

Secondary syphilis

Secondary syphilis presents 1–2 months after the primary chancre (which may be unreported). Erythematous, slightly scaly, macules or papules appear mainly on the trunk. There may be darker red macules on the palms and soles, as well as smooth or eroded papules on the tongue and oral mucosa, moist perineal papules (condylomata lata), annular lesions and pustules. Lymphadenopathy is usually present. Secondary syphilis can mimic pityriasis rosea and other red scaly disorders.

Seborrhoeic dermatitis

The term ‘seborrhoeic dermatitis’ has been used to describe a number of different clinical entities. It is most widely used for a particular dermatitis that occurs in areas of skin that have a high density of sebaceous glands, namely the scalp, the central ‘T-zone’ of the face, and the upper chest and back (not the anogenital area, see p. 316). It is due to a reaction to a Pityrosporum yeast, which is part of the normal flora at these sites.

As true seborrhoeic dermatitis can only occur in the setting of active sebaceous glands, the diagnosis should only be made in the first 3 months of life or after puberty has begun. The sites of predilection are the scalp, inner eyebrows and paranasal folds. The quality of the scale is more greasy than that of an eczema at other sites and the degree of pruritus and discomfort is usually minimal. The degree of erythema varies and mild cases present as neonatal cradle cap or adolescent dandruff.

Atopic eczema is common on the scalp of infants and is differentiated from seborrhoeic dermatitis by increased pruritus and discomfort, a harsher drier scale and occurrence after the age of two months. It is important not to diagnose scalp eczema as seborrhoeic dermatitis as eczema will be further irritated by shampoos and ‘cradle cap’ creams.

Management

• Gently debride any built-up crust with a non-irritating product such as olive oil, bath oil or a soap substitute. Only if very thick scale is present should salicylic acid creams be used.
• Settle erythema with 1% hydrocortisone cream.
• The use of an anti-yeast shampoo (e.g. 2% ketoconazole) may be helpful in more recalcitrant cases.
• Adolescents with seborrhoeic dermatitis may have to wash their hair more frequently.

Lichen striatus

Lichen striatus usually presents on a limb as a unilateral linear eczematous rash following the developmental lines of the skin. On close inspection, there are often collections of tiny flat-topped papules, coalescing into scaly lines that may stretch the full length of the limb. It may remain static for a period of months or a couple of years, before spontaneously resolving. It may be pruritic but usually not significantly so.

The cause of the eruption is an inflammatory reaction in a streak of skin that has a genetic abnormality (mosaicism). The genetic difference of the streak is so subtle that the skin is phenotypically and functionally normal until a trigger, mostly a viral infection, induces an inflammatory reaction against the abnormal skin. As the condition is self-limiting, no treatment is necessary if the condition is asymptomatic. Moderate-strength to potent topical steroid creams can help with any pruritus.

Eczematous rashes

The term ‘eczematous rashes’ covers several common conditions that are characterised by erythema, itching and disruption to the epidermis with oozing, crusting, fissures or excoriations. The degree of epidermal disruption may be minimal so that the presentation of atopic eczema may be with just red dry patches. Alternatively, the degree of epidermal disruption may be severe, with oedema and widespread vesiculation (e.g. plant contact dermatitis, which is discussed under vesiculobullous rashes, p. 282).

Atopic eczema – general issues

The term ‘atopic eczema’ covers a range of presentations that depend on the age of the child and on the child’s individual sensitivities. Several of these presentations are best seen as separate diseases. Clinical features and specific management suggestions are discussed under the individual headings below. However, some generalisations apply to most children with atopic eczema subtypes.

Atopic eczema usually begins in infancy. It commonly involves the face, and often the trunk and limbs as well. In older children, the rash may be widespread but is often localised to flexures. Erythema, weeping, excoriation and, rarely, vesicles may be seen in acute lesions. Chronic lesions may show scale and lichenification. In some children, the lesions are more clearly defined, thickened discoid areas that may intermittently be itchy. There is usually a cyclical pattern of improvement and exacerbation.

Families who present to the ED with atopic eczema often have children with chronic and severe disease requiring frequent, time-consuming applications of topical medicines and wet dressings. These children may have recurrent infections, particularly with Staphylococcus aureus or herpes simplex. Failure to thrive may be present. A mild, normocytic (occasionally microcytic) anaemia of chronic disease can occur. Severe psychosocial and behavioural problems are common in these children although often hidden from medical staff. Parents may be under enormous stress with financial, marital and other problems secondary to the child’s eczema. These problems need to be identified and addressed.

Atopic eczema – general management principles

• Education. Parents need to know that treatments are effective in controlling the disease. They should be aware of the principles of avoiding relevant triggers and settling the inflammation.
• Avoid irritants. The following may worsen atopic eczema: soaps, bubble baths, prickly clothing, including clothing worn by adults carrying babies, seams and labels on clothing, car seat covers, sand, carpets, overheating or contact with pets. Smooth cotton clothing is preferred.
• Avoid heat. Overheating increases itch. Most parents overdress young children. Outer clothing should be removed when entering warm environments. Bedding and baths should be kept comfortably cool.
• Keep the skin moist. Use a moisturiser such as sorbolene with 10% glycerine, aqueous cream or paraffin ointment (50:50 white soft paraffin/liquid paraffin) as often as a few times a day if necessary.
• Treat inflammation. In mild or moderate cases, steroid creams can be used intermittently with good effect. Hydrocortisone 1% is usually adequate. If not, moderate potency (e.g. betamethasone valerate 0.02%) or potent (e.g. mometasone 0.1% or methylprednisolone 0.1%) ointment can be used for exacerbations. Widespread long-term use of moderate potency steroids to the skin can cause atrophy or striae, especially on the face, the nappy area of infants, and sites of rapid growth such as the thighs of pubertal girls. Although expensive, pimecrolimus 1% is a useful alternative in some situations. Oral steroids are rarely indicated in atopic eczema. For chronic atopic eczema on the limbs, zinc and tar combinations are alternatives to steroids. Topical calcineurin inhibitors (tacrolimus and pimecrolimus) are increasingly used as an adjunct to topical steroid therapy but are expensive.
• Control itch. Advise parents to avoid saying ‘stop itching’ all the time and to distract the child instead. Wet bandaging is very helpful if warranted. Antihistamines are often unhelpful but if the itch is not controlled by other measures, they may be tried.
• Wet dressings. Wet dressings are bandages applied over topical moisturiser or corticosteroid ointments two to four times a day. They cool the skin and are effective in controlling flares of eczema, settling troublesome focal patches of eczema and reducing the need for corticosteroid. They are well tolerated by children although cumbersome to apply. However, if the initial application is done by a parent at home, acceptance of the treatment may be prejudiced by pre-existing conflict between the child and parent over treatment regimens. If possible, wet dressings should ideally be commenced by trained staff in hospital.
• Treat infection. Weeping and yellow crusted areas that do not respond to therapy may indicate secondary bacterial or herpetic (see p. 328) infection. Take cultures and treat with simple wet dressings and oral cephalexin 30 mg kg−1 (max 500 mg) three times daily. For recurrent bacterial infection, use bleach baths, e.g. White King Bleach (4.2%) 3 tablespoons (= 45 mL) in a quarter full bath (approx 60 L).
• Severe cases. Do not accept that nothing more can be done. Children with chronic severe eczema need to be referred for psychosocial support and for assessment as to whether they warrant admission to hospital, oral prednisolone, narrow-band ultraviolet B therapy or other systemic immunosuppressive therapy.2

Atopic eczema – dietary principles

A normal diet is indicated in most children with eczema. If a child has immediate urticarial reactions to a particular food, that food should be avoided. No alteration should otherwise be made to an infant’s or child’s diet unless appropriate conventional therapy, as above, has not worked. In difficult cases, particularly in infants, consider a formal allergy assessment. Restrictive diets without professional supervision should be avoided.

Babies with a first-degree relative with eczema have a 50% chance of developing eczema. For these babies, no modifications to the mother’s diet are recommended during pregnancy and breast-feeding. Exclusive breast-feeding for the baby is recommended for a minimum of 4 months for a number of reasons. If exclusive breast-feeding is not possible, supplementation with partially hydrolysed formula may reduce the risk of eczema. The use of soy formula has no role in the prevention of allergy but is to be considered if there is clinical suspicion of dairy allergy. Peanuts and other nuts should be avoided until 1 year of age.

Atopic eczema – admission to hospital

Children with eczema who attend EDs often do so because the parents have become increasingly desperate to get their child’s skin under control. Admission to hospital can be very helpful. You should consider admitting the child if any of the following circumstances apply.

• A child is missing school because of atopic eczema. If so, they should generally be admitted to hospital for intensive treatment.
• A child has severe impetiginisation or you have concerns about sepsis.
• A child has widespread eczema herpeticum.
• The family has social, financial or mental health issues that make home treatment difficult.
• Education of the parents in an emergency setting is difficult because they speak a language other than English.
• The parents exhibit significant stress or impending breakdown.
• Outpatient management has not given a satisfactory response.
• An adolescent has widespread chronic eczema that affects their lifestyle (wears long clothing in summer, won’t swim, etc.).

Atopic eczema – use of topical steroid preparations

The use of topical steroids remains a pivotal component of eczema management. It is important to settle the eczema and restore the natural integrity of the skin. If eczema is left untreated, the natural barrier of the skin remains disrupted and the skin is more prone to react to other eczema triggers. Any scratching will further flare the skin and a worsening cycle is created. Topical cortisone preparations are used to break this cycle and heal the skin. They should not be used as prophylaxis on normal skin. The preparations are best prescribed in ointment formulation as these are more moisturising. Creams may be used if ointments are poorly tolerated. As a general rule, topical corticosteroids are extremely safe. Side effects are very uncommon if used appropriately.

Always ask parents if they are treating their children with herbal creams. Any herbal cream that gives dramatic clearing should be assumed to contain corticosteroid products until proven otherwise. A British study in 2003 looked at a number of herbal creams given to children for eczema.3 Over 80% of those tested had illegal potent or very potent corticosteroid additives. Similar results have been found in previous studies.

Systemic effects of topical steroid use

Suppression of the pituitary-adrenal axis can occur if potent topical corticosteroids are used over most of the skin surface continuously for many weeks, but this is an uncommon clinical scenario. If a child is using large amounts of topical corticosteroids in combination with inhaled corticosteroids and/or occasional oral cortisone therapy, you should consider adrenal suppression. Steroid therapy should not be abruptly stopped in this situation.

Local effects of topical steroid use

Irritation or allergy to one of the constituents of the topical steroid occurs in a few children. Apart from this, local side effects rarely occur. Inappropriate use can lead to atrophy, striae, telangiectasia, purpura, cataracts and juvenile rosacea. Care is required when treating the face, anogenital areas, flexures and any areas of rapid growth where the skin is already under tension (e.g. breasts in adolescent females). In these situations, permanent striae can occur within weeks. Precipitants of eczema should continue to be sought if the need for topical corticosteroids is ongoing. It should be explained to patients that once the eczema has cleared, the topical corticosteroids should be ceased. This is more important in darker-skinned individuals, where post-inflammatory hyperpigmentation may be mistaken by the patient for active disease.

The topical calcineurin inhibitors, tacrolimus and pimecrolimus, are now available as steroid-sparing agents. However, their expense currently limits their use for widespread disease.

Atopic eczema – generalised infantile

Some infants present in the first 6 months of life with red, scaly and excoriated lesions covering much of the trunk and often the limbs, scalp and face as well. These infants are typically irritable and often sleeping and feeding poorly. The parents are often highly stressed by the difficulties with managing the child. Appropriate treatment usually leads to a dramatic change in the baby’s behaviour and the family dynamics.

A detailed history should be taken to identify any exacerbating factors in the child’s environment. Examination will often reveal considerable dermographism and urticarial change. Allergy to foods is common in this setting and allergy testing is useful. Foods in the maternal diet can trigger allergy in a breast-fed baby. Consider whether admission for wet dressings is required. Consider whether secondary bacterial or herpes infection is present. Treat with a bland emollient such as paraffin ointment once or twice daily. Use hydrocortisone 1% ointment on the face and methyl-prednisolone 0.1% to the body daily to gain rapid control of the skin. Arrange follow up within a week or two if using significant amounts of potent topical steroid preparations. Skin prick testing and appropriate allergen avoidance may be useful in the longer term.

Atopic eczema – facial

Some infants will present with facial lesions. There may or may not be eczema elsewhere. Facial eczema may be secondarily infected with Staphylococcus aureus, resulting in weeping and crusting (Fig. 12.1.10). Saliva is often a significant exacerbating factor. Herpes simplex virus infection needs to be considered (look for the typical monomorphic erosions, see p. 284). Treat with ointment moisturiser several times daily and, if indicated, oral cefalexin 30 mg kg−1 (max 500 mg) three times daily for 1 week. If appropriate follow up can be assured, use methyl-prednisolone 0.1% ointment for a few days to gain rapid control of the skin. Arrange follow up within a week to avoid problems from prolonged steroid use. Avoidance of irritating factors such as using napkin wipes on the face and general management measures are required to prevent relapse.

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Fig. 12.1.10 Facial eczema with secondary impetiginisation in a 10-month-old boy.

Atopic eczema – perioral eczema vs. juvenile rosacea

Perioral eczema

Refers to eczema round the mouth. This is common in infancy and early childhood. Irritation from saliva is the main cause. Occasionally, intolerance or allergy to foods can play a role in the older child. Confluent patches of erythema with weeping and superficial erosion occur in acute eczema. Management involves settling the active patches with a brief period of topical corticosteroid ointment and then trying to minimise irritation from saliva. This is difficult in the dribbling infant. Thicker moisturisers such as 50% white soft/liquid paraffin (Dermeze) may be used both as a moisturiser and as a barrier on the skin. In persistent cases, use pimecrolimus 1% cream or tacrolimus 0.03% ointment.

Juvenile rosacea

Is often called ‘perioral dermatitis’ and confused with perioral eczema but it is not a true dermatitis. It is better thought of as a subset of rosacea. The most common clinical setting is following the use of topical steroids in a young child who is genetically predisposed to develop this condition. The morphology is quite different from perioral eczema. Erythematous papules occur around the mouth but spare the skin immediately adjacent to the lips. Other facial areas may be involved. The papules are essentially distinct from each other but may coalesce at times. Topical steroids tend to temporarily settle the inflammation and then cause a rebound flare, and patients are often under the false impression that the topical steroids are the only effective therapy. Treatment involves the cessation of all topical steroids on the skin in this area and the introduction of an appropriate antibiotic. Use erythromycin in children or tetracyclines in adolescents. Pimecrolimus 1% cream may give added benefit. Resolution usually takes 3–4 weeks of therapy. It is important to warn patients who have been actively using topical steroids that there will be a rebound flare before they begin to see improvement.

Atopic eczema – periorbital

Periorbital eczema is usually associated with sensitivity to airborne allergens, especially house dust mites, cat dander and pollens. Consideration of the occasions when the itch is worst will often indicate the causative agent. Formal skin prick testing, allergen avoidance measures, moisturiser, pimecrolimus 1% cream and follow up are required. In atypical cases, consider allergic contact dermatitis, irritant contact dermatitis and molluscum.

Atopic eczema – sudden worsening or urticarial flare

Children with eczema occasionally present to the ED with an acute worsening of previously stable eczema. This should prompt a search for an underlying cause. Look for any evidence of scabies, which can easily be overlooked amongst the background eczema – other family members may be itchy. Look for secondary bacterial infection. Consider if herpes simplex virus infection (p. 283) may be present. Small papules in widespread patches of eczema may be from subtle molluscum lesions. The child may have developed an irritant or allergic contact sensitivity to their topical treatments or other agents. Search for and treat any exacerbating factors. Arrange early follow up for management of the underlying eczema.

Often a sudden worsening with a dramatic increase in itch in a child with previously mild eczema is caused by viruses or allergy to drugs, food or environmental agents. They are often dermographic (i.e. they urticate in response to pressure on the skin) and it is likely that the cause of the flare is a subtle urticaria. When they itch, the scratching causes more urticaria, thereby causing more itch and escalating problems. These flares will often abate over a few days or weeks and the addition of a regular antihistamine will considerably help to control the symptoms. Uncommonly, metabolic triggers such as iron deficiency or thyroid disease may present with increased itch and worsening of eczema.

Atopic eczema – molluscum

Molluscum infection can trigger a marked local or generalised reaction in children. Presentation to the ED follows the development of widespread itchy and excoriated eczematous lesions in surrounding skin, usually on the lateral chest and axillary region or between the thighs. If the child has a previous history of atopic eczema, the molluscum lesions may be overlooked or hidden in the eczema. A careful history may reveal that clear, firm papules were present at some stage. A careful examination may reveal some typical molluscum or some residual papules in the centre of eczematous patches. Treat as previously described (under molluscum, p. 293).

Atopic eczema – flexural

While flexural eczema is the most common form of atopic eczema in children, it is rarely a cause for attendance at the ED unless sudden worsening has been triggered by secondary bacterial infection, secondary herpetic infection, acute irritant or allergic contact sensitivity or molluscum infection. Search for and treat any exacerbating factors. General principles of moisturisation, reducing overheating and avoiding irritants are usually adequate to regain control.

Atopic eczema – discoid

Discoid eczema is characterised by chronic focal circular crusted lesions 1–5 cm in diameter. These children may have an associated psoriatic tendency. The discoid lesions are thickened, oozing and itchy. They are relatively resistant to therapy. Secondary staphylococcal infection is present in most cases. Intensive and prolonged therapy is needed to break the cycle of itch, lichenification and infection. Oral cephalexin 30 mg kg−1 (max 500 mg) three times daily, ointment moisturiser, potent topical steroid ointment and regular wet dressings for 2 weeks may be adequate, but therapy may need to be prolonged. Follow up is mandatory. Hospital admission, intralesional steroid injections, ultraviolet light therapy or oral ciclosporin may all be considered.

Atopic eczema – juvenile plantar dermatosis

Juvenile plantar dermatosis is characterised by erythema, dryness and cracking of the anterior sole and the under surface of the toes. It is usually seen in mid-childhood and tends to occur in children with a tendency for increased sweating. The child may or may not have atopic eczema elsewhere. Both feet are usually symmetrically involved in the weight-bearing skin on the soles. Juvenile plantar dermatosis may persist for years and exacerbations may be associated with painful fissures. The differential includes tinea (which should be excluded by culture), psoriasis and contact dermatitis, which can all present with red scaly lesions on the soles. Cotton socks, leather shoes and regular ointment moisturiser three-times daily should be used. Cotton socks can be worn over the moisturiser. Minimise exposure of cracked skin to carpets and other irritants. Topical potent corticosteroid ointments may be necessary. Follow up is needed.

Atopic eczema with systemic associations

Eczematous skin lesions can also be associated with:

• Immunodeficiency syndromes. Thrombocytopenia, immunodeficiency and eczema are seen in Wiskott–Aldrich syndrome. Petechiae, failure to thrive, recurrent infections, diarrhoea or haematological abnormalities may suggest this or other immunodeficiencies that are variably associated with eczema. Netherton’s syndrome should be considered if neonatal-onset eczema is associated with failure to thrive and sparse hair.
• Multiple food allergies with consequent dietary restrictions and secondary nutritional and psychosocial problems.
• Metabolic or nutritional disorders. Phenylketonuria often presents with eczema. Less typical eczematous lesions, more prominent in periorificial areas, are seen in biotin, essential fatty acid and zinc deficiency syndromes. Malnutrition and organoacidaemias, e.g. methylmalonicacidaemia, can result in similar lesions.

Irritant contact dermatitis

The most common forms of irritant contact dermatitis in children are irritant napkin dermatitis (p. 317), juvenile plantar dermatosis (see above) and lip licking. Lip licking refers to a dermatitis caused by chronic exposure to saliva. Usually the application of saliva by the child is presumed by the carers to be secondary to the dermatitis rather than causative, and may not be mentioned. Lip licking often presents with a clearly defined ring of dermatitis around the mouth but the pattern of involvement may vary considerably depending on the behaviour of the child. Any habit that spreads saliva in a particular direction will affect the pattern of the dermatitis. Acidic foods, artificial colours, preservatives and toothpaste may contribute to the irritation. Treatment requires education, frequent topical ointment barrier applications (initially many times daily) and immediate treatment of any relapse. A short period of topical pimecrolimus 1% cream may be needed. Secondary bacterial or candidal infection is rarely present.

Allergic contact dermatitis

Acute allergic contact reactions (e.g. to plants) often cause vesiculation and are considered under vesiculobullous rashes (p. 282). Chronic exposure to a contact allergen presents with erythema, itch and lichenification. The site of reaction usually suggests the cause: axillary rashes from deodorants, ears from earrings, lips and eyes from make-up, lower abdomen from nickel buttons on pants, wrist from watch, perioral from toothpaste and so on. However, the trigger may be overlooked. For example, an itchy eczematous patch on the scalp may be due to a metal stud in a cap that is not being worn at the time of presentation to the ED. Consider allergic contact dermatitis if a child has persistent eczema in an unusual distribution.

Allergic contact dermatitis – ‘black henna’ reactions

In recent years, several children have presented to EDs with an allergic reaction to ‘black henna’. Henna is widely used in Asian countries as a traditional skin colouring agent. It is dark brown. Many street vendors use cheap black hair dye instead, calling it ‘black henna’, often mixing this with other agents such as petrol to enhance absorption. These tattoos last for some weeks. These tattoos contain paraphenylenediamine, a strong contact sensitiser that should not be applied to the skin.

Three to 10 days after the application of the tattoo, the child may notice discomfort, itch, erythema and swelling. This may progress over the next 2 weeks to blistering and scabbing of the tattoo site, sometimes with ulceration. Generalised itch and urticaria may be present and it may take months for complete resolution to occur. These children may develop a long-lasting cross-sensitivity to sun screens, hair dyes, black clothing and cosmetics.

Treat with ointment moisturiser and potent topical corticosteroid or oral prednisolone if warranted.

Generalised dry skin – ichthyosis

Ichthyosis refers to generalised scaly skin. There are several forms. Some ichthyoses only affect the skin but several have associated abnormalities in other organs.

Ichthyosis vulgaris is the commonest of the ichthyoses. It has autosomal dominant inheritance, and occurs as an isolated finding in 1 in 200 children.

X-linked ichthyosis is less common and may be undiagnosed for years or decades. About one-third of affected boys are diagnosed for the first time by an observant clinician during an emergency attendance for an unrelated problem. A fine scaling at birth is later replaced by larger brown scales. Diagnosis is confirmed by enzyme analysis for the affected steroid sulfatase gene. Boys with X-linked ichthyosis are usually otherwise normal but need to be monitored for hypogonadism, cryptorchidism, anosmia, short stature and mental retardation. Female carriers may have obstetric difficulties leading to prolonged labour.

In Sjögren–Larsson syndrome, a yellow-brown lichenified appearance is present in infancy. This evolves into a more florid scaling with a symmetric spastic paralysis and mental retardation. In some trichothiodystrophies, ichthyosis is associated with brittle hair and mental and growth retardation. Several ichthyoses are linked with deafness, cataracts or other eye problems. Mild, generalised scaling may be the first feature in later-onset Refsum disease, before development of multiple visual problems, deafness and neuropathy.

Eczema does not usually present as generalised dryness in babies. Unless there is a clear history of familial ichthyosis vulgaris, an infant with significant dryness should be referred for assessment by a skin specialist.

Ectodermal dysplasias are a heterogeneous group of conditions characterised by congenital, non-progressive abnormalities of hair, teeth, nails and sweat glands. The skin is dry and may be hyperpigmented. Deficient sweating may cause overheating in infants at any time and in older children in summer. Children may present with undiagnosed recurrent fevers or with heat prostration, collapse or death. Teeth are often poorly developed or absent. Cleft lip and palate, limb abnormalities and mucous retention in the upper airway and ear may be present. Accurate diagnosis, genetic counselling, dental and audiological review, appropriate moisturiser and topical cortisone use if needed, education about avoiding overheating and regular follow up are all required.

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