Oncocytic meningioma: a case report and review of the literature.

Oncocytic meningioma is an uncommon variant of meningioma, with only 20 reported cases to date, that is histologically characterized by the presence of neoplastic cells with granular eosinophilic cytoplasm rich in mitochondria. We present the clinicopathological features of a case of oncocytic meningioma in a 49-year-old Chinese female, along with a literature review. Brain computed tomography and magnetic resonance imaging demonstrated a slightly hyperintense mass located in the right frontal region and attached to the dura. In addition, it was homogeneously enhanced following contrast administration. She underwent gross total surgical resection of the tumor and adjacent dura. Grossly, the well-demarcated, nonencapsulated mass had a solid and tan-white appearance with soft and rubbery consistency. The lesions were composed primarily of sheets, nests, and cords of large polygonal bland cells with finely granular eosinophilic cytoplasm rich in mitochondria. Mitotic figures were rare, and necrosis was absent. There was no infiltration of the dura or brain cortex. Immunohistochemical staining revealed that the neoplastic cells were positive for vimentin, epithelial membrane antigen, antimitochondrial antibody, and progesterone receptor, whereas MIB-1 stained only approximately 1% of the tumor cells. This is the first known report of an oncocytic meningioma arising in a Chinese patient. The patient was followed for 19 months without any evidence of metastasis or recurrence.