[Cutaneous histiocytic sarcoma: report of one case].

Histiocytic sarcoma (HS) is a rare hematologic malignancy with morphologic and immunophenotypic evidence of histiocytic differentiation. Previously known as "true histiocytic lymphoma", the tumor follows an aggressive clinical course. Involvement of lymph nodes, skin, and extranodal sites has been described. Among the latter, approximately 29 cases involving the skin have been reported. On pathology, the lesion shows a diffuse proliferation of large epitheloid histiocytes with marked pleomorphism. We report a 78 year-old male who presented with a nodular lesion in the forehead, involving the skin and son tissue. The pathological diagnosis was a HS. The patient was lost from follow up.