Abstract: A 32-year-old female presented with erythemas，plaques and ulcers on the vulva and anus accompanied with itching for more than 1 year. Physical examination showed pale red infiltrated plaque with ulceration and exudates on the surface around the vulva and anus，and purulent secretions can be seen. Pathology showed diffuse infiltration of lymphocytes, eosinophilic granulocytes, and histiocytoid cells in the superficial dermis. The proliferative histiocytoid cells showed mild atypia，partly with kidney-shaped nuclei. Immunohistochemical examination showed that histiocytoid cells were positive for S-100 and CD1a，and weakly positive for CD68(20%+) and Ki-67(30% + ) . The diagnosis of adult localized Langerhans cell histiocytosis was made.

Key words: Langerhans cell histiocytosis, adult, vulva, perianal