Primary central nervous system histiocytic sarcoma.

Histiocytic sarcoma is a rare, lymphohematopoietic malignant neoplasm composed of tumor cells showing morphologic and immunophenotypic features of mature tissue histiocytes. Involvement of the central nervous system (CNS) as either a part of a systemic disease or as a primary lesion has rarely been described so far. We present a case of primary CNS histiocytic sarcoma in an adult patient and review the literature on this rare entity.