A rare case of Langerhans cell histiocytosis with perianal involvement in a 34 year old white man is presented. During nineteen months this patient had a complaint of anal pain with bleeding, due to a large perianal ulcer. The initial diagnosis was Crohn's disease, anal tuberculosis, syphilis, pyoderma gangrenosum or donovanosis. After the third biopsy, the surgical specimens showed microscopic changes suggestives of Langerhans cell histiocytosis. The imunohistochemical study was positive to S100 protein and CD1a. The patient was treated with six doses of intralesional triancinolona and oral thalidomide for three months. Treatment was well tolerated and complete resolutions of peri-anal ulcer occurred.
langerhans cell histiocytosis; X histiocytosis; perianal histiocytosis; langerhans cell; ulcer
