[Oncocytic meningioma. Case report].

Among the histological variants of meningiomas the oncocytic subtype is rarely observed. Up-today, only six cases of oncocytic meningioma are described. This subtype of meningiomas shows an aggressive behavior and recurrences are more frequent. We describe a case of oncocytic meningioma in a 78-years-old woman. The patient had a history of breast cancer diagnosed 9 years before the brain biopsy; bilateral mastectomy and adjuvant chemotherapy was performed. She had a right frontal tumour measuring 3 cm in diameter. The patient is alive and well eleven months after surgery. The tumour was composed by large polygonal neoplastic cells with finely granular eosinophilic cytoplasm. Neoplastic cells were arranged in sheets and nests delimited by thin fibrous septa rich in vessels. Psammomatous bodies were also present. Mitoses were rare and necrosis was absent. Oncocytic differentiation was demonstrated by conventional histology and immunohistochemistry. Immunohistochemistry revealed a strong and diffuse positivity for antimitochondrial antiserum, vimentin and EMA; a focal reactivity for cytokeratin was observed. The rarity of oncocytic meningiomas is underlined with only six cases described in the world literature. The immunophenotypic profile and the differential diagnosis of the neoplasm is discussed and the concept of oncocytic meningioma as a distinct entity of tumour is emphasized.