A 6-month-old boy with persistent pruritic eruption. Langerhans cell histiocytosis.

A previously healthy 6-month-old boy presented to the pediatric dermatology clinic for evaluation of a persistent, pruritic eruption. This eruption involved the scalp, extremities, and inguinal creases and was intensely pruritic. The patient had been previously treated with multiple topical corticosteroids and antifungals, all with minimal improvement. He born at full term and was otherwise well and thriving. Review of systems was negative. Examination revealed erythematous to yellow scaly, greasy plaques, some with underlying purpuric papules in the frontal, temporal, and vertex of the scalp, post-auricular regions, and the conchae of both ears. There were also scattered papules and purpura noted in the inguinal creases, and hyperkeratotic yellow papules on the extensor extremities. He had no abnormal lymphadenopathy or hepatosplenomegaly. The remainder of his examination was normal. A diagnostic skin biopsy was performed.