INTRACYTOPLASMIC GRANULOFILAMENTOUS INCLUSION-BODIES IN A MENINGIOMA - IMMUNOHISTOCHEMICAL AND ULTRASTRUCTURAL STUDIES

A case of cerebellar tentorial meningioma, with abundant, large, eosin ophilic intracytoplasmic inclusions, was studied immunohistochemically and ultrastructurally. These intracellular inclusions were periodic a cid-Schiff negative and ultrastructurally appeared as a condensation o r aggregation of numerous intracytoplasmic intermediate filaments. The se inclusions were not related to microvillus-lined ductules, indicati ng that these inclusions were distinct from pseudopsammoma bodies. In addition, these inclusions were intensely immunopositive for vimentin, whereas staining for glial fibrillary acidic protein, epithelial memb rane antigen, cytokeratin, neurofilament, desmin, actin, or type IV co llagen was negative. To our knowledge, this is the second reported cas e of meningioma with such unusual inclusions, but the first one to dem onstrate that the intracytoplasmic intermediate filaments and their re lated inclusions were mainly composed of vimentin.