Secretory meningioma: a diagnostic pitfall.

Abstract

Secretory meningioma is a rare subtype of meningiomas, displaying epithelial and secretory differentiation of meningothelial cells. It has unique radiological, morphological, and immunohistochemical features, but runs a benign course. Radiological picture because of the variable degrees of peritumoral edema can be confused with aggressive neoplasms. Morphologically, it is difficult to distinguish secretory meningioma from other tumors having a clear cell appearance and aggressive clinical behavior. Retrospective analysis over a period of 16 years (1997-2012) brought out five cases diagnosed as secretory meningioma. The slides were restained and subject to special stains and immunohistochemistry and the clinical details were retrieved. On histopathology, the tumors showed a characteristic vacuolated appearance due to the presence of variably sized intracytoplasmic lumina. Another unique feature was the presence of hyaline inclusions within these intracytoplasmic lumina and in the intercellular spaces. These inclusions were periodic acid-Schiff positive diastase-resistant, yellowish-orange on Elastic Van Giesson stain and strongly carcinoembryonic antigen positive. Owing to its rarity and unique morphology secretory meningioma poses a diagnostic challenge to the pathologists. As this tumor follows a benign course, it is crucial to correctly diagnose this entity to avoid unnecessary over treatment.