Adult cutaneous Langerhans cell histiocytosis.

A 24-year-old male presented with a 4 year history of a crusted erythematous papular eruption of the scalp and external auditory meati and a 12 month history of painful perianal ulceration. A diagnosis of Langerhans cell histiocytosis was made and confirmed by skin histology. Extensive investigation revealed no systemic involvement. Rapid improvement occurred after intravenous 2-chlorodeoxyadenosine but relapse of perianal lesions occurred within 5 months. Local radiotherapy to the perianal region resulted in a complete remission sustained over 12 months.