Regressing ulcerative histiocytosis.

A 15-year-old girl presented with many round to oval erythematous indurated plaques on the trunk, scalp, and proximal portion of the extremities. The individual lesions showed ulceration within a short period but spontaneously healed after 2 or 3 months. The main histological feature was dermal proliferation of rather mature histiocytes that were regarded as neither inflammatory nor neoplastic, with subsequent destruction of normal dermal tissue architectures. Lymph nodes, bone marrow, and internal organs were not involved. The lesions were improved neither by potassium iodide therapy nor by combined therapy of corticosteroid and cyclophosphamide, but the patient recovered by clofazimine after a 2-year course. We considered this case to be an unusual form of cutaneous histiocytic proliferation, which we tentatively termed "regressing ulcerative histiocytosis."