Primary intracerebral plasma cell granuloma: a light, immunocytochemical, and ultrastructural study of one case.

A case of primary intracerebral plasma cell granuloma without meningeal attachment is presented. Histologically, the lesion showed two different patterns. At the center, it displayed the features of a benign fibrous histiocytoma. At the periphery, a mixture of polyclonal plasma cells, lymphocytes, and "epithelial-like" cells was observed. Electron microscopy and immunocytochemistry confirmed the histiocytic nature of the "epithelial-like cells." The differential diagnosis and histogenesis of such a lesion are discussed.