Assessing the Skin

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chapter 19 Assessing the Skin

Laura A. Finlayson

It is not only fine feathers that make fine birds.

AESOP

Problems of the skin or its appendages are very common in children, and it is therefore important to be able to assess the skin in a logical and organized manner. In fact, a skin condition is the chief complaint for approximately 15% of patients in a family doctor’s or pediatrician’s office and is a secondary concern for other patients. A number of cutaneous conditions occur almost exclusively in infants and children, and most dermatoses (skin conditions) that are seen in adults are also seen in children. There are many hereditary and congenital skin conditions (genodermatoses). Most of the common infectious diseases of childhood have cutaneous manifestations, and skin involvement is a major feature of several multisystem disorders.

A child’s skin is more reactive than that of an adult. It is more likely to blister and is more susceptible to warts and certain other infections. When children are ill, they are more likely than adults to have multisystem manifestations of illness. For example, they may demonstrate a complex of symptoms that could include rash, fever, anorexia, lethargy, and diarrhea. Paradoxically, physicians often regard skin diseases as relatively trivial (i.e., the least of the patient’s problems) in the vast scope of medicine, but the patient may be more concerned about cutaneous problems than about a more serious internal problem that is not visible to others. For example, a teenager with psoriasis and cystic fibrosis may consider the psoriasis the more difficult of the two to accept.

Some physicians consider skin diseases difficult to diagnose for a variety of reasons. Because skin has a limited repertoire of reaction patterns, several disease processes may cause similar rashes. In addition, there are many variations in the appearance, location, and severity of both common and rare diseases of the skin, so a condition may look quite different in different patients. Finally, many skin conditions have one or more unhelpful protracted Latin names that are difficult to remember.

Despite these factors, it is possible to develop a simple, practical approach to most dermatologic problems. If you can assign a skin condition to a broad morphologic group on the basis of its appearance, you can learn or refer to lists of the conditions within the group. After a time, you will find it easier to recognize the primary lesions that identify the morphologic groups and the variations in common skin conditions in each group. Table 19–1 lists the most common skin problems seen in children and classifies them by morphologic appearance.

TABLE 19–1 Morphologic Classification of Common Pediatric Skin Conditions

Skin Lesion	Examples
Macules	Freckles, junctional nevi, tinea versicolor
Patches	Café au lait spots port-wine stains, vitiligo
Maculopapular rashes	Viral exanthems, drug eruptions
Papules	Warts, molluscum contagiosum, insect bites, compound nevi
Papules with burrows	Scabies
Papules with comedones	Acne
Plaques (nonscaly)	Mastocytomas, sebaceous nevus
Papulosquamous eruptions	Psoriasis, pityriasis rosea, lichen planus, fungal infections
Vesiculobullous eruptions	Friction blisters, acute contact dermatitis, herpes infections, bullous impetigo, staphylococcal scalded skin syndrome
Eczematous eruptions	Atopic dermatitis, seborrheic dermatitis, contact dermatitis, diaper dermatitis
Nodules or tumors	Epidermoid or pilar cysts, neurofibromas, lipomas
Alopecia	Alopecia areata, trichotillomania, tinea capitis

This chapter reviews the history and physical examination of the skin and illustrates the approach to diagnosis through case history examples. Color plates illustrate many of the problems discussed and some nevi commonly seen by pediatricians. Details and photographs of most pediatric dermatologic conditions can be found in the works cited in the Suggested Readings.

Key Point

Classifying a child’s skin disease into one of several broad groups (e.g., maculopapular, papulosquamous, vesiculobullous) on the basis of the history and physical examination is a good start, even if a specific diagnostic label cannot be applied.

Obtaining the History of Skin Problems

As always, a detailed history is fundamental in assessing each child’s problem. Clues from casual inspection may direct your line of questioning and make the interview more efficient; but even if the diagnosis is obvious from a single glance, take the time to obtain a thorough history.

When children are too young to give a history firsthand, you can generally rely on the parents’ interpretations. A baby who scratches constantly is almost certainly experiencing pruritus, although some itchy infants are irritable and sleep poorly but scratch very little, and very young infants are not developmentally able to scratch. Children are suggestible; a 7-year-old who is asked, “Does your rash itch?” will almost certainly answer, “Yes.” Instead, ask the child whether the rash bothers him or her in any way, and ask the parent whether the child sleeps well at night or is scratching frequently. Pruritus from any cause is always worse at night because

1. There are fewer external distracting stimuli

2. The warmth of the bedclothes causes vasodilation in the skin, which exacerbates itching.

Some skin conditions, such as poison ivy, dermatitis, and lichen planus, are intensely itchy, and relieving the pruritus may be more important than improving the rash.

Remember that you are seeing the child’s skin problem at a particular moment in its evolution. The parents’ description of its appearance at the onset and careful documentation of its evolution are therefore very important. Acute skin eruptions are usually dynamic, and the distribution or morphology may change rapidly. By contrast, chronic eruptions are more likely to have a stable appearance.

Key Point

Acute skin eruptions can change rapidly. A rash that cannot be diagnosed one day may be quite obviously diagnosable the next day.

Some patients and parents are incredibly observant when it comes to skin, and others notice no details at all. Let both the patient and the parents give their descriptions, then ask for clarification. Use terms they will understand, such as those suggested in Table 19–2.

TABLE 19–2 Examples of Terminology Most Parents Understand

Medical Term	Lay Term
Macule	Dot
Papule	Little bump
Nodule	Big bump
Plaque	Raised or thickened area
Vesicle	Little blister
Bulla	Big blister
Pustule	Pus pocket, pimple
Desquamation	Scaling, flaking
Crusts	Scabs
Excoriations	Scratch marks
Comedones	Blackheads, whiteheads

History of present illness

Your questions should cover the following points:

• Onset of the skin problem

• Symptoms, such as itching, pain, tenderness, restriction of movement

• Signs noted, such as bleeding, discharge, or scaling

• Evolution, changes in appearance, or distribution over time since the onset of the problem

• Presence of systemic symptoms, such as fever, malaise, anorexia, weight loss, headache, or diarrhea

• History of contact with others with a similar problem or known infectious disease

Some words used to describe skin eruptions are nonspecific and are often used improperly by patients or physicians. An example of such nonspecificity is the word blister. It is important to confirm that they are referring to true vesicles or bullae because that will narrow your differential diagnosis. If a child presents with a blistering eruption, in addition to the described history, you should ask the following questions (in words that the parents can understand):

• How long does each blister last?

• Did all of the blisters start at once, or do some heal and new ones appear in other locations?

• Are the blisters localized or generalized?

• Do they arise on an erythematous (red) base or on normal skin?

• What color is the fluid within them—serous (clear), purulent (cloudy), sero-purulent, hemorrhagic (bloody), or sero-hemorrhagic (pink)?

• Are the blisters tense or flaccid? To help answer this, you can ask how easily they break. The more superficial flaccid bullae break open quickly, leaving a raw eroded area.

• Have there been any blisters in the mouth or in the genital area (mucocutaneous lesions)?

Key Point

Ask about recent travel outside the country to properly diagnose nonendemic infections or to find out about environmental conditions, such as high heat and humidity, which can induce or exacerbate a skin condition.

For a rash, ask what the child and parents think caused it. Their suspicions may turn out to be correct, or they may have an unfounded fear (e.g., skin cancer) that can be put to rest.

Ask for details of exacerbating or relieving factors and of seasonal influences on the course of the skin problem. Some types of dermatitis become worse in the winter because of the lower humidity. The influence of sun exposure is an important factor. Conditions, such as lupus erythematosus, are exacerbated by sun exposure, whereas psoriasis usually improves significantly with sun exposure. In some cases, it is important to have a history of recent travel and exposures to wooded areas, animals, and insects.

Skin care regime, topical treatments, and medication history

Often, you need to find out what routine care is given to the skin and the clothing that is in contact with it. For instance, in eczematous eruptions, you must learn how often the child is bathed, what kind of soap and detergent are used, and what moisture creams or other preparations have been applied to the skin.

Frequently, several topical agents have been applied before the child visits a physician, and it is important to find out what has been used before and after the problem began.

Some proprietary medications may be bland and soothing and provide symptomatic relief. Others may contain active ingredients that are inappropriate for the child’s problem or are in the wrong concentration. Some may contain ingredients that are common topical sensitizers and may aggravate the skin problem. Ask about any prescribed topical medications used before the current assessment of the child. Often, parents may not remember the names of topical preparations. If necessary, call the pharmacist to find out what was prescribed.

Obtain a detailed history of all prescribed or over-the-counter oral medications, including doses and duration of administration. Ask specifically about nonprescription medications, such as acetylsalicylic acid, acetaminophen, and cold remedies. Drugs can cause rashes of all descriptions, although the most common are maculopapular eruptions, urticaria, and erythema multiforme. Ask about any previous reactions to medications, and document the type and severity of each.

Past medical history, functional inquiry, and immunization record

Request details of any previous skin problems; these may or may not be related to the presenting problem. Some conditions, such as atopic dermatitis, can resolve, only to flare up years later under certain circumstances.

Other medical problems may or may not be related or relevant. For example, atopic dermatitis is frequently seen in individuals who also have asthma, hay fever, or other allergies, since these conditions can be inherited together.

Family history

Obtaining a family history is important, because numerous skin conditions are genetically determined, and many chronic dermatoses are considered hereditary, although they may be polygenic or exhibit incomplete penetrance. Sometimes an environmental trigger may unmask a disease in an individual who is genetically predisposed. For example, a streptococcal sore throat commonly precedes the development of guttate psoriasis.

A patient presenting with a genodermatosis or a neurocutaneous syndrome may or may not have a known family history of the disorder. Absence of a family history may be due to the following factors:

• A high mutation rate (50% for neurofibromatosis)

• Recessive inheritance or incomplete penetrance causing the condition to skip generations

• Some skin conditions occur on sites usually covered by clothing and are not considered a proper topic of conversation between generations.

• False-positive family histories are also occasionally obtained when past diagnoses have been wrong or are misunderstood.

At times, the family history is not as important for diagnosis as for prognosis. For example, a teenager with multiple large and irregular nevi who has a family history of malignant melanoma is at significant risk for development of a melanoma; therefore, advise him or her about sun protection, regular self-examinations, and periodic professional examination to prevent melanoma or detect it in an early, curable stage. The positive family history is a significant risk factor in this case.

Approach to the Physical Examination

When you begin the physical examination of the child’s skin, you should have in mind a general differential diagnosis based on the details of the history. Sometimes, after examining the skin, you will find that additional history is required. For example, if the history suggests an exacerbation of atopic dermatitis and you note multiple crusted vesicles on examination, you need to ask about the patient’s contact with people who have cold sores because eczema herpeticum is a likely cause of this flare-up.

Good light is essential to adequate examination of the skin. Its importance is often overlooked. Natural light is best, and it may help to move the patient near a window. However, natural light is not always available in clinics and hospital rooms, and fluorescent light may distort colors and minimize subtle skin changes. For the examination of localized lesions, using a spotlight can help. Also, a magnifying glass helps you appreciate details.

Examine the entire skin surface

Always look at the entire skin surface, even if the history suggests a localized problem. The dermatologic examination includes the entire skin, the visible mucous membranes, and the skin appendages (hair, nails, and sweat glands), for the following reasons:

1. There may be involvement of other skin sites that no one has recognized, such as a small raised scaly plaque on the scalp or nail pitting in a child with possible psoriasis.

2. Other cutaneous manifestations may be found that relate to the presenting complaint, such as reticulate white plaques on the buccal mucosa of a child with possible lichen planus. These findings can help confirm or rule out a diagnosis.

The extent, distribution, and severity of a skin problem are best appreciated by undressing the child and viewing most of the skin at once. You can, however, perform this step after the child is more comfortable with the examination procedure. Older children feel more self-conscious about being unclothed for a skin examination than they are by the same extent of undress for a chest or neurologic examination. Give the child a gown, and leave the room while he or she changes into it. It is acceptable to uncover and examine one area at a time in a gowned patient, but do not try to peek under tight clothing. For children younger than 2 years, a gown is unnecessary. The toddler’s sense of modesty is relatively undeveloped, and it is much easier to examine the child properly when he or she is wearing nothing more than a diaper or underpants.

Wear examining gloves if the child has eroded or oozing lesions, when you examine the mucous membranes, and if you suspect a contagious condition such as scabies. Generally, however, gloves are not necessary and tend to make the youngster feel uncomfortable.

Key Point

You can learn much if you simply start the examination by assessing the distribution and extent of the skin problem and the presence or absence of symmetry. Is the condition generalized or localized? Are the scalp, face, and neck involved? Is the eruption predominantly proximal or distal, and are the palms and soles involved? Are there any mucous membrane lesions?

Primary lesions

A lesion is referred to as primary if it is the first change to occur in the skin because of the disease. Secondary lesions can be caused by external factors, such as scratching and secondary infection, or may evolve from the primary lesion. Proper assessment of the type of primary lesions present is essential. The patient may have just one type of primary lesion or a variety of primary and secondary lesions.

Nodules and Tumors

Nodules and tumors are circumscribed and elevated lesions that are larger than papules. Nodules arise from deeper structures, therefore displaying depth as well as elevation (Plate 19–4). Tumors can arise from deep structures, the dermis, or the epidermis. As with papules, describe the shape, outline, elevation, depth, surface characteristics, firmness of a nodule or tumor, and its mobility on palpation.

Vesicles and Bullae

A vesicle is a small (less than 1 cm) raised cavity containing fluid. A bulla is a larger, fluid-filled lesion (more than 1 cm). Both are called blisters by lay persons. Look at the distribution and arrangement, which may be important for diagnostic purposes. For example, the blisters in poison ivy contact dermatitis are commonly linear in arrangement (Plate 19–5), whereas those of herpes simplex are clustered closely together. Note whether the blisters arise on erythematous skin, such as in a blistering contact dermatitis, or on apparently normal skin, such as with friction blisters. Describe the color of fluid within the lesions—serous, hemorrhagic, or a combination.

Noting whether the vesicles and bullae are tense or flaccid provides clues to the layers of skin in which they arise. Blisters that are more superficial, such as those of bullous impetigo, are more flaccid because fewer layers of cells make up the roof of the lesion, whereas those arising from deeper layers tend to be tense. The pathologic process is also likely to be more superficial if there are multiple erosions present because these blisters rupture easily, and the roof of the lesion is no longer present. Often, a small peripheral rim of epidermis is still adherent around the periphery of an erosion, indicating that this eruption is vesiculobullous (see later discussion) even though no blisters remain intact.

Check for the Nikolsky sign in vesiculobullous conditions. The Nikolsky sign exists if the layers of skin can be easily separated with a gentle rubbing or shearing force (Plate 19–6). This phenomenon is seen in staphylococcal scalded skin syndrome, toxic epidermal necrolysis, pemphigus, and some forms of epidermolysis bullosa.

Search for any vesicles or erosions on the visible mucosa. It is unusual to see blisters in the intact state in the mouth because there is so much friction and trauma from eating and talking.

The group of disorders in which blisters are the primary lesions is called vesiculobullous eruptions. There are many causes of vesiculobullous eruptions in children. Some are rare hereditary blistering disorders, such as epidermolysis bullosa. Common infectious diseases, such as varicella (Plate 19–7), bullous impetigo, and herpes simplex, produce vesiculobullous eruptions. Skin conditions due to exogenous factors, such as friction and sunburn, frequently cause blistering. A vesicular reaction may be caused by various types of contact dermatitis, either irritant or allergic in origin. (A prime example of allergic contact dermatitis is that caused by poison ivy, shown in Plate 19–5.) Vascular reactions, such as erythema multiforme and some forms of vasculitis, may cause vesicles.

Key Point

Many drugs can cause various patterns of blistering on the skin. Drug eruptions are most commonly maculopapular or urticarial, but almost every pattern of skin eruption can be caused by drugs.

Finally, there is a rare group of primary vesiculobullous disorders in children, including chronic bullous dermatosis of childhood, pemphigus, bullous pemphigoid, and dermatitis herpetiformis.

Pustules

Pustules are similar to vesicles, but the fluid within them is a purulent (containing pus) exudate. Try to determine whether a pustule is associated with a hair follicle (folliculitis). Pustules frequently represent skin infections, which can be either a primary (e.g., bullous impetigo) or a secondary infection of another skin condition (e.g., infected atopic dermatitis). Pustules are formed by an abnormal accumulation of leukocytes with or without microorganisms and cellular debris. Not all pustules, therefore, represent infection, although infection is the most common cause. For example, the pustules of pustular psoriasis are sterile if the pus is cultured, and they arise from the accumulation of neutrophils in the epidermis.

Wheals or Urticaria

A wheal is a transient raised lesion caused by edema within the skin and dilation of the local blood vessels. The wheal is the primary lesion in urticaria (lay term: hives). Wheals are erythematous and vary greatly in size, shape, and number. Urticarial eruptions are usually due to the release of histamine and other chemical mediators. The individual lesions resolve within 24 hours, often within 1 to 2 hours, but they may continue to evolve at different sites. The course of an urticarial eruption may, therefore, be arbitrarily defined as acute (lasting fewer than 6 weeks) or chronic (longer than 6 weeks).

Angioedema is a similar process that occurs deeper in the skin, giving a less well-demarcated localized swelling, which often is tender rather than pruritic. Patients prone to urticaria often have dermatographism, in which the wheals form in lines wherever pressure is exerted on the skin, such as under tight clothing. It can be demonstrated by firmly stroking the letter X on the patient’s back; if dermatographism is present, a urticarial wheal will form within a few minutes (Plate 19–8).

Comedones

A comedone is a plug in a hair follicle. Usually occurring in areas with many sebaceous glands, such as the face, upper back and chest, comedones are a primary lesion in acne. The plug consists of clumped keratin and sebum. Comedones can be either closed (whiteheads) or open (blackheads). The black color of open comedones is due to oxidation of the plugged material when it is exposed to air.

Burrows are faint linear tunnels in the layers of the superficial epidermis, usually 2 to 7 mm long (Fig. 19–1). They are the primary lesions in scabies and are most easily found between the fingers and around the wrists and ankles. The female scabies mite (Sarcoptes scabiei) and some of her eggs may be visible only as a tiny black dot at the blind end of the burrow.

FIGURE 19–1 Scabies with typical burrows.

(From Zitelli BJ, Davis HW: Atlas of Pediatric Physical Diagnosis, 5th ed. Philadelphia, Mosby, 2007.)

Patients with scabies usually have numerous excoriated inflammatory papules with some burrows among them. The morphology of scabies may vary with age. In an infant, there may be lesions over the entire body, including the face and scalp, whereas in older children and adults, the head area is spared. Infants may present with pustules on the palms and soles, a pattern less common in older individuals. Chronic scabies that has gone undiagnosed for months may appear as crusted nodules rather than the more typical papules and burrows (Plate 19–9).

Telangiectasia

Telangiectasia represents permanently dilated superficial blood vessels in the skin. On diascopy (viewing through a microscope slide pressed firmly against the skin), they blanch almost completely but fill again as soon as the pressure is released. Primary telangiectasia can be hereditary, idiopathic, or a manifestation of one of several rare syndromes. Secondary telangiectasia may be related to localized inflammation, collagen vascular diseases, sun damage, liver disease, or pregnancy.

Secondary lesions

Secondary lesions can evolve from primary lesions or can arise from external factors, such as scratching.

Scaling

Scaling, which results from the accumulation of desquamating skin cells, can be primary or secondary. It is commonly seen in disorders of keratinization. Normally, cells that are fully keratinized desquamate (flake off) invisibly on the skin surface. Scaling occurs if there is hyperproliferation of the epidermis, as in psoriasis, or if there is an abnormality in cohesion of keratinocytes that causes them to clump together abnormally, as in some types of ichthyosis. Describe the type of scaling as accurately as possible: coarse, fine, white, yellow, silvery, greasy, peripheral, or adherent.

Crusts

Crusting results from the accumulation of dried exudates or transudates on the skin (Plate 19–10). A crust from dried serous fluid is honey-colored and easily dislodged; a crust from purulent material is brown and tightly adherent; and a crust from sanguineous or bloody fluid is red-brown to black and tightly adherent. Crusts are seen on any oozing eruption, such as infected eczema or a vesiculobullous eruption.