Microcystic meningiomas.

Four patients (two male and two female) underwent surgery for the removal of tumors with clinical and radiographic features typical of a meningioma. Despite an incorrect intraoperative frozen section diagnosis in two cases, the tumors were totally resected because the surgeon was convinced of the meningiomatous nature of the lesion. Subsequent histology revealed features of a microcystic meningioma and careful scrutiny of paraffin sections showed that each of the tumors contained occasional typical meningothelial cellular whorls which were a helpful diagnostic clue. Ultrastructural examination and the absence of GFAP confirmed the diagnosis. Close liaison with the neurosurgeon, on the part of the pathologist and an awareness of this unusual variant of meningioma should prevent misdiagnosis and inappropriate treatment of a potentially curable tumor.