Malignant fibrous histiocytoma of the meninges. Histological, ultrastructural, and immunocytochemical studies.

A case of malignant fibrous histiocytoma arising from the meninges in a 12-year-old boy is reported. This tumor presented as an extracerebral hemorrhagic mass in the left frontal lobe without obvious invasion of the underlying brain. Histologically, a malignant tumor with the characteristic storiform pattern of malignant fibrous histiocytoma with focal areas of hemorrhage was observed. Ultrastructurally, fibroblastic cells, undifferentiated cells, histiocytic-type cells, multinucleated tumor giant cells, and xanthomatous cells were distinctly seen. The possible cell of origin of these meningeal tumors and their prognosis are discussed. The significance of considering this entity in the differential diagnosis of those tumors of the central nervous system with a spindle-cell or xanthomatous component is discussed, and the value of ultrastructural and immunocytochemical study with glial fibrillary acidic protein in the diagnosis is stressed.