Very rarely, Langerhans cell histiocytosis (an increase in Langerhans cells in the skin) may simulate seborrhoeic dermatitis. The cause for this is unknown. In small children it may cause death as the infiltrate may also involve internal organs. The condition is differentiated from seborrhoeic dermatitis by the presence of purpura and erosions as well as treatment resistance.
Management of seborrhoeic dermatitis is essentially the same as that for atopic dermatitis.2 Scalp scaling responds to treatment with liquor picis carbonis (LPC, or coal tar solution) 2% and salicylic acid 2% in a moisturising base, and the nappy area is treated with a combination of 1% hydrocortisone and an anticandidal cream, such as nystatin or an imidazole. It is a good idea to follow up the infant to ensure that this is not the first presentation of a chronic dermatosis such as atopic dermatitis or infantile psoriasis.
Acne is usually thought of as a condition seen in teenagers, but it may also occur in babies and prepubertal children. Because acne is an androgen-dependent condition occurring in genetically predisposed patients, it may be seen in children at times when there is a high enough androgen level to permit expression of the tendency. Neonatal acne is the term used to describe acne occurring in the first two years of life. The acne is often predominantly comedonal and its onset is soon after birth. It is more common in boys, varies in severity and often needs no treatment, but it can be severe enough to cause scarring. Parents should be warned that neonatal acne may, and often does, recur at puberty. Children with early onset acne usually go on to suffer from teenage acne.
Acne is also seen in prepubertal children after the age of 8 years, when the androgens secreted at adrenarche stimulate sebaceous glands in predisposed individuals. It is not usually necessary to investigate for androgen excess unless there are other concerning signs such as excess facial hair. Acne presenting for the first time after 12 months of age and before the age of 8 years raises the possibility of androgen excess. Such patients should be referred to a dermatologist or an endocrinologist.
Neonatal acne is self-limiting and usually remits by 12 months of age, but it may persist to 24 months. If treatment is needed, topical therapy usually used for mild teenage acne is appropriate. This includes topical tretinoin 0.025% cream once daily and erythromycin 2% gel once daily. Rarely, neonatal acne may be nodulocystic and can be treated with oral isotretinoin to prevent permanent scarring. In this case referral to a paediatric dermatologist is required.3 For prepubertal children with acne, topical therapy is also often adequate. Oral antibiotic therapy is usually not required, but in severe cases, oral erythromycin may be used (tetracycline is contraindicated in this age group because it may stain teeth).
Other childhood rashes
Although psoriasis is less common in children than in adults, up to 30% of cases have their onset in childhood and in about 5% the onset is before the age of 2 years. The average age of diagnosis in childhood cases is about 8 years.