Congenital, spontaneously regressing histiocytosis: case report and review of the literature.

A patient had numerous skin lesions at birth and they regressed over the next few weeks. Results of the peripheral blood smear and bone marrow examinations were normal. The diagnosis of self-healing histiocytosis was substantiated by the clinical course and characteristic histology. This was subsequently confirmed by the electron microscopic finding of Langerhans' granules within the histiocytic cells, which were positive for S100 by immunoperoxidase.