Langerhans cell histiocytosis: an uncommon presentation, successfully treated by thalidomide.

Langerhans cell histiocytosis (LCH) is a rare disease and generally affects children under 15 years of age. Adult onset form and cutaneous features at presentation are uncommon. There are some options for treatment of the skin lesions of LCH such as topical and intralesional corticosteroid, nitrogen mustard, etc., which are not completely curative. Herein, we report a case of perianal LCH in a 20-year-old man with one-year history of recalcitrant well-demarcated, erythematous, and ulcerated plaque surrounding the anal orifice, with pain and difficulty in defecation that was successfully treated with thalidomide.