Skin

Published on 21/03/2015 by admin

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Last modified 21/03/2015

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8 Skin

George Millington, Nandu Thalange

Introduction

All children will have a condition affecting their skin at some time. Most conditions are acute and transient, such as the exanthem accompanying acute viral infections like parvovirus, rubella and measles (see Chapter 16). These skin manifestations serve as a useful diagnostic guide but may not require specific treatment. Some, such as atopic eczema, will be chronic and potentially debilitating without appropriate management. Still others will be permanent and require care of the skin lesion and also of potential complications such as the epilepsy seen with port wine haemangioma in Sturge–Weber syndrome (see also Chapter 14, p. 204).

Inflammation

Chronic skin inflammation is usually due to eczema, although more rarely psoriasis is the cause. Self-limiting acute inflammatory disorders are commonly due to allergic or hypersensitivity reactions. The distribution of the rash is often highly characteristic and suggests the diagnosis (Figure 8.1).

Figure 8.1 Distribution of rash in various skin conditions.

Atopic eczema

Eczema is often described as the ‘itch that rashes’. Itch and dryness are key components of atopic eczema. Secondary infection, usually with Staphylococcus aureus and streptococci, is common, and should be suspected whenever the skin is weeping and crusted (as in Case 8.1). Viral superinfection, such as with herpes simplex or varicella, may cause dramatic exacerbations with marked systemic upset – eczema herpeticum.

Eczema is the commonest skin complaint of childhood, affecting 10–15% of all children. Eczema is an inflammatory eruption, with erythema and papules or vesicles on a dry background. Secondary scaling and crusting occur commonly, progressing to lichenification in chronic cases. Although a chronic condition, 90% of cases remit by 15 years of age.

Case 8.1

A girl with a dry itchy rash

Jade, a 14-month-old girl, was taken to the GP because she was distressed, miserable and would not sleep. She had a longstanding dry itchy rash over the wrists, in front of her elbows, behind her knees, and behind her ears. Recently the rash had become vesicular with weeping and crusting. She had previously had episodes of wheeze with viral infections and a single episode of a red blotchy rash after eating egg. Her mother had asthma and her father suffered from seasonal rhinitis.

The ‘itch–scratch cycle’ is a key factor. Dry skin itches and the child scratches. The trauma of scratching releases inflammatory mediators, causing more itch and may also break the epidermal barrier and lead to infection. The distribution of the rash varies with age, the face, head and trunk being more commonly affected in young infants, while the extensor and flexural surfaces of the limbs are more commonly affected in older children. There is a genetic predisposition in many cases with a history of eczema or other atopic diseases in close family members.

Trigger factors are not always obvious but include secondary staphylococcal infection, over-washing with soap, stress resulting in scratching, or, occasionally, dietary allergens such as egg or cow’s milk protein.

Contact eczema or dermatitis is uncommon in childhood although an allergic causation should be considered. This may be obvious, as e.g. with nickel sensitivity when the rash is limited to the area in contact with nickel. Common culprits are watchstraps or earrings. In some cases, biological detergents, or lanolin, found in many emollient creams, may cause contact dermatitis.

Seborrhoeic dermatitis has overlapping features but it appears preferentially on the scalp with a yellowish greasy appearance, often with more scaling, and it usually appears early in infancy. Scabies can resemble eczema due to the combination of scratching and inflammation/superinfection.