Bullous impetigo

This is an uncommon but potentially serious blistering form of impetigo, the most superficial form of bacterial infection, seen particularly in the newborn (Fig. 24.1). It is most often caused by Staphylococcus aureus. Treatment is with systemic antibiotics, e.g. penicillinase-resistant penicillin (see also Ch. 14).

Melanocytic naevi (moles)

Congenital moles occur in up to 3% of neonates and any that are present are usually small. Congenital pigmented naevi involving extensive areas of skin (i.e. naevi >9 cm in diameter) are rare but disfiguring (Fig. 24.2) and carry a 4–6% lifetime risk of subsequent malignant melanoma. They require prompt referral to a paediatric dermatologist and plastic surgeon to assess the feasibility of removal.

Melanocytic naevi become increasingly common as children get older and the presence of large numbers in an adult may be indicative of childhood sun exposure. Prolonged exposure to sunlight should be avoided and sunscreen preparations with a sun protection factor exceeding 20 should be applied liberally to exposed skin in bright weather and reapplied every few hours.

Malignant melanoma is rare before puberty, except in giant naevi. However, in adults, the incidence of malignant melanoma has increased dramatically over the past 30 years. Risk factors for melanoma include a positive family history, having a large number of melanocytic naevi, fair skin, repeated episodes of sunburn and living in a hot climate with chronic skin exposure to the sun.

Albinism

This is due to a defect in biosynthesis and distribution of melanin. The albinism may be oculocutaneous, ocular or partial, depending on the distribution of depigmentation in the skin and eye (Fig. 24.3). The lack of pigment in the iris, retina, eyelids and eyebrows results in failure to develop a fixation reflex. There is pendular nystagmus and photophobia, which causes constant frowning. Correction of refractive errors and tinted lenses may be helpful. In a few children, the fitting of tinted contact lenses from early infancy allows the development of normal fixation. The disorder is an important cause of severe visual impairment. The pale skin is prone to sunburn and skin cancer. In sunlight, a hat should be worn and high factor barrier cream applied to the skin.

Epidermolysis bullosa

This is a rare group of genetic conditions with many types, characterised by blistering of the skin and mucous membranes. Autosomal dominant variants tend to be milder; autosomal recessive variants may be severe and even fatal. Blisters occur spontaneously or follow minor trauma (Fig. 24.4). They need to be differentiated from scalds. Management is directed to avoiding injury from even minor skin trauma and treating secondary infection. In the severe forms, the fingers and toes may become fused, and contractures of the limbs develop from repeated blistering and healing. Mucous membrane involvement may result in oral ulceration and stenosis from oesophageal erosions. Management, including maintenance of adequate nutrition, should be by a multidisciplinary team including a paediatric dermatologist, paediatrician, plastic surgeon and dietician.

Collodion baby

This is a rare manifestation of the inherited ichthyoses, a group of conditions in which the skin is dry and scaly. Infants are born with a taut parchment-like or collodion-like membrane (Fig. 24.5). Emollients are usually applied to moisturise and soften the skin. The membrane becomes fissured and separates within a few weeks, usually leaving either ichthyotic or less commonly, normal skin.

Infantile seborrhoeic dermatitis

This eruption of unknown cause presents in the first 2 months of life. It starts on the scalp as an erythematous scaly eruption. The scales form a thick yellow adherent layer, commonly called cradle cap (Fig. 24.7a). The scaly rash may spread to the face, behind the ears and then extend to the flexures and napkin area (Fig. 24.7b). In contrast to atopic eczema, it is not itchy and the child is unperturbed by it. However, it is associated with an increased risk of subsequently developing atopic eczema. Mild cases will resolve with emollients. The scales on the scalp can be cleared with an ointment containing low-concentration sulphur and salicylic acid applied to the scalp daily for a few hours and then washed off. Widespread body eruption will clear with a mild topical corticosteroid, either alone or mixed with an antibacterial and antifungal agent if appropriate.

Atopic eczema (atopic dermatitis)

The prevalence of atopic eczema in children in the UK is about 20%. A genetic deficiency of skin barrier function is important in the pathogenesis of atopic eczema. Onset of atopic eczema is usually in the first year of life. It is, however, uncommon in the first 2 months, unlike infantile seborrhoeic dermatitis, which is relatively common at this age. There is often a family history of atopic disorders: eczema, asthma, allergic rhinitis (hay fever). Around one-third of children with atopic eczema will develop asthma. Exclusive breast-feeding may delay the onset of eczema in predisposed children but does not appear to have a significant impact on the prevalence of eczema during later childhood. Atopic eczema is mainly a disease of childhood, being most severe and troublesome in the first year of life and resolving in 50% by 12 years of age, and in 75% by 16 years.

Itching

Box 24.2   Some itchy rashes

• Atopic eczema

• Chickenpox

• Urticaria/allergic reactions

• Contact dermatitis

• Insect bites/papular urticaria

• Scabies

• Fungal infections

• Pityriasis rosea.

Management

A number of treatment modalities are available.

Avoiding irritants and precipitants

It is advisable to avoid soap and biological detergents. Clothing next to the skin should be of pure cotton where possible, avoiding nylon and pure woollen garments. Nails need to be cut short to reduce skin damage from scratching, and mittens at night may be helpful in the very young. When an allergen such as cow’s milk has been proven to be a precipitant, it should be avoided.

Emollients

These are the mainstay of management, moisturising and softening the skin. They should be applied liberally two or more times a day and after a bath. They include ointments such as one containing equal parts of white soft paraffin and liquid paraffin. Ointments are preferable to creams when the skin is very dry. A daily or alternate day bath using an emollient oil as a soap substitute is also beneficial.

Topical corticosteroids

These are an effective treatment for eczema, but must be used with care. Mildly potent corticosteroids, such as 1% hydrocortisone ointment, can be applied to the eczematous areas twice daily. Moderately potent topical steroids play a pivotal role in the management of acute exacerbations, but their use must be kept to a minimum. They should be applied thinly and their use on the face should be generally avoided. Excessive use of topical steroids may cause thinning of the skin as well as systemic side-effects. However, fear of these side-effects should not deter their use in controlling exacerbations.

Eczema

Box 24.3

Causes of exacerbation of eczema

• Bacterial infection, e.g. Staphylococcus, Streptococcus spp.

• Viral infection, e.g. herpes simplex virus

• Ingestion of an allergen, e.g. egg

• Contact with an irritant or allergen

• Environment: heat, humidity

• Change or reduction in medication

• Psychological stress

• Unexplained.

Immunomodulators

In children over 2 years old, short-term topical use of tacrolimus or pimecrolimus may be indicated for eczema not controlled by topical corticosteroids and where there is a risk of important adverse effects from further topical steroid use.

Occlusive bandages

These are helpful over limbs when scratching and lichenification are a problem. They may be impregnated with zinc paste or zinc and tar paste. The bandages are worn overnight or for 2–3 days at a time until the skin has improved. For widespread itching in young children, short-term use of wet stockinette wraps may be helpful; diluted topical steroids mixed with emollient are applied to the skin and damp wraps fashioned for trunk and limbs are then applied with overlying dry wraps or clothes.

Antibiotics or antiviral agents

Antibiotics with hydrocortisone can be applied topically for mildly infected eczema. Systemic antibiotics are indicated for more widespread or severe infection. Eczema herpeticum is treated with systemic aciclovir.

Itch suppression is with an oral antihistamine. The newer second-generation antihistamines are not sedative. Antihistamines can be useful in raising the itching threshold so that scratching is reduced.

Dietary elimination

Food allergy may be present if the child reacted with immediate symptoms to a food, or in infants and young children with moderate or severe atopic eczema, particularly if associated with gut dysmotility (colic, vomiting, altered bowel habit) or failure to thrive. It may even occur in young infants with severe eczema who are exclusively breast-fed at the time. The most common food allergies are to egg, cow’s milk and peanut. However, any food may be implicated in an eczema flare-up. Dietary elimination for 4–6 weeks is required to detect a response. A trial of an extensively hydrolysed protein formula or amino acid formula in place of cow’s milk formula is also recommended for bottle-fed infants under 6 months old with severe atopic eczema that has not been controlled by optimal treatment with emollients and mild topical corticosteroids. Dietary elimination should be carried out with the advice of a dietician to ensure complete avoidance of specific food constituents and that the diet remains nutritionally adequate. A food challenge is required to be fully objective. Children can usually tolerate the offending foods by the age of 3–4 years with the important exception of peanut allergy, which usually persists.

Summary

Psychosocial support

In most children, eczema is mild and can be controlled with emollients and mildly potent topical steroids, and additional psychological support is not required. However, eczema can be sufficiently severe to be disrupting both to the child and to the whole family. The parents and the child need considerable advice, help and support from health professionals, other affected families or fellow sufferers. In the UK, the National Eczema Society provides support and education about the disorder.

These are caused by the human papillomavirus, of which there are well over 100 types. Warts are common in children, usually on the fingers and soles (verrucae). Most disappear spontaneously over a few months or years and treatment is only indicated if the lesions are painful or are a cosmetic problem. They can be difficult to treat, but daily application of a proprietary salicylic acid and lactic acid paint or glutaraldehyde (10%) lotion can be used. Cryotherapy with liquid nitrogen is effective treatment but can be painful and often needs repeated application, and its use should be reserved for older children.

Molluscum contagiosum

This is caused by a poxvirus. The lesions are small, skin-coloured, pearly papules with central umbilication (Fig. 24.12). They may be single but are usually multiple. Lesions are often widespread but tend to disappear spontaneously within a year. If necessary, a topical antibacterial can be applied to prevent or treat secondary bacterial infection, and cryotherapy (2–3 s only) can be used in older children, away from the face, to hasten the disappearance of more chronic lesions.

Dermatophyte fungi invade dead keratinous structures, such as the horny layer of skin, nails and hair. The term ‘ringworm’ is used because of the often ringed (annular) appearance of skin lesions. A severe inflammatory pustular ringworm patch is called a kerion (Fig. 24.13).

Tinea capitis (scalp ringworm), sometimes acquired from dogs and cats, causes scaling and patchy alopecia with broken hairs. Examination under filtered ultraviolet (Wood’s) light may show bright greenish/yellow fluorescence of the infected hairs with some fungal species.

Rapid diagnosis can be made by microscopic examination of skin scrapings for fungal hyphae. Definitive identification of the fungus is by culture. Treatment of mild infections is with topical antifungal preparations, but more severe infections require systemic antifungal treatment for several weeks. Any animal source of infection also needs to be treated.

Scabies is caused by an infestation with the eight-legged mite Sarcoptes scabiei, which burrows down the epidermis along the stratum corneum. Severe itching occurs 2–6 weeks after infestation and is worse in warm conditions and at night.

In older children, burrows, papules and vesicles involve the skin between the fingers and toes, axillae, flexor aspects of the wrists, belt line and around the nipples, penis and buttocks. In infants and young children, the distribution often includes the palms (Fig. 24.14), soles and trunk. The presence of lesions on the soles can be helpful in making the diagnosis. The head, neck and face can be involved in babies but is uncommon.

Diagnosis is made on clinical grounds with the history of itching and characteristic lesions. Although burrows are considered pathognomonic, they may be hard to identify because of secondary infection due to scratching. Itching in other family members is a helpful clinical indicator. Confirmation can be made by microscopic examination of skin scrapings from the lesions to identify mite, eggs and mite faeces.

Pediculosis

Pediculosis capitis (head lice infestation) is the most common form of lice infestation in children. It is widespread and troublesome among primary school children. Presentation may be itching of the scalp and nape or from identifying live lice on the scalp or nits (empty egg cases) on hairs (Fig. 24.15). Louse eggs are cemented to hair close to the scalp and the nits (small whitish oval capsules) remain attached to the hair shaft as the hair grows. There may be secondary bacterial infection, often over the nape of the neck, leading to a misdiagnosis of impetigo. Sub-occipital lymphadenopathy is common. Once infestation is confirmed by finding live lice, treatment is by applying a solution of 0.5% malathion to the hair and leaving it on overnight. The hair is then shampooed and the lice and nits removed with a fine-tooth comb. Treatment should be repeated a week later. Permethrin (1%) as a cream rinse would be an alternative application; it is left on for 10 min only. Flammability of alcohol-based lotions should be noted. Wet combing to remove live lice (bug-busting) every 3–4 days for at least 2 weeks is a useful and safe physical treatment, particularly when parents treat with enthusiasm.

Summary

Scabies

• Very itchy burrows, papules and vesicles – distribution varies with age

• Scratching leads to excoriation, secondary eczematous or urticarial reaction often with secondary bacterial infection

• Not only the child but the whole family need treatment.

Pityriasis rosea

This acute, benign self-limiting condition is thought to be of viral origin. It usually begins with a single round or oval scaly macule, the herald patch, 2–5 cm in diameter, on the trunk, upper arm, neck or thigh. After a few days, numerous smaller dull pink macules develop on the trunk, upper arms and thighs. The rash tends to follow the line of the ribs posteriorly, described as the ‘fir tree pattern’. Sometimes the lesions are itchy. No treatment is required and the rash resolves within 4–6 weeks.

Alopecia areata

This is a common form of hair loss in children and, understandably, a cause of much family distress. Hairless, single or multiple non-inflamed smooth areas of skin, usually over the scalp, are present (Fig. 24.17); remnants of broken-off hairs, visible as ‘exclamation mark’ hairs may be seen at the edge of active patches of hair fall. The more extensive the hair loss, the poorer the prognosis, but regrowth often occurs within 6–12 months in localised hair loss. Prognosis should be more guarded in children with atopic disorders.

Granuloma annulare

Lesions are typically ringed (annular) with a raised flesh-coloured non-scaling edge (unlike ringworm) (Fig. 24.18). They may occur anywhere but usually over bony prominences, especially over hands and feet. Lesions may be single or multiple, are usually 1–3 cm in diameter, and tend to disappear spontaneously but may take years to do so. There is also a subcutaneous form.

Acne vulgaris

Acne may begin 1–2 years before the onset of puberty following androgenic stimulation of the sebaceous glands and an increased sebum excretion rate. Obstruction to the flow of sebum in the sebaceous follicle initiates the process of acne. There are a variety of lesions, initially open comedones (blackheads) or closed comedones (whiteheads) progressing to papules, pustules, nodules and cysts. Lesions occur mainly on the face, back, chest and shoulders. The more severe cystic and nodular lesions often produce scarring. Menstruation and emotional stress may be associated with exacerbations. The condition usually resolves in the late teens, although it may persist.

Topical treatment is directed at encouraging the skin to peel using a keratolytic agent, such as benzoyl peroxide, applied once or twice daily after washing. Sunshine, in moderation, topical antibiotics or topical retinoids may be helpful. For more severe acne, oral antibiotic therapy with tetracyclines (only when over 12 years old, because they may discolour the teeth in younger children) or erythromycin is indicated. The oral retinoid isotretinoin is reserved for severe acne in teenagers unresponsive to other treatments.

Urticaria

Urticaria (hives), characterised by flesh-coloured weals, is described in Chapter 15 and the management of anaphylaxis in Chapter 6.

Papular urticaria is a delayed hypersensitivity reaction most commonly seen on the legs, following a bite from a flea, bedbug, or animal or bird mite. Irritation, vesicles, papules and weals appear and secondary infection due to scratching is common. It may last for weeks or months and may be recurrent.

Erythema multiforme

Box 24.5

Causes of erythema multiforme

• Herpes simplex infection

• Mycoplasma pneumoniae infection

• Other infections

• Drug reaction

• Idiopathic

Hereditary angioedema is a rare autosomal dominant disorder caused by a deficiency or dysfunction of C1-esterase inhibitor. There is no urticaria, but subcutaneous swellings occur, often accompanied by abdominal pain. The trigger is usually trauma. Angioedema may cause respiratory obstruction. Specific treatment of a severe acute attack is with a purified preparation of the inhibitor, but replacement therapy with fresh frozen plasma can be used as a short-term measure.