MENINGIOMA, SECRETORY VARIANT
Touch preparations show hypercellular cohesive clusters of uniform densely packed cells (Fig. 2). Higher-power examination reveals spindled to oval cells with eosinophilic cytoplasm, smooth nuclear outline and fine evenly distributed chromatin. The cells show syncytial arrangement and whorl formation (Fig. 3). Also seen are occasional intra-nuclear cytoplasmic invaginations (nuclear pseudo-inclusions) and scattered eosinophilic globules (Fig. 4)
On H&E, the tumor cells form lobules which are surrounded by thin collagenous septae (Figs. 5 and 6). The tumor cells are largely uniform with oval nuclei that on occasion show central clearing (Figs. 7 and 8). The tumor shows scattered concentric arrangement of cells in whorl formation.
The cytologic and histologic features of this tumor is characteristic of meningioma. An additional striking feature in is the presence of scattered eosinophilic PASD-positive secretory material (Figs. 8 and 9)
Immunostaining with both EMA (Fig. 13) and CEA (Figs. 10 and 11) shows strong positivity of the secretory material. The tumor cells were only focally positive with EMA (Fig. 12) and show a low proliferative activity on Ki67 (Fig. 14).
Meningiomas are estimated to constitute between 13% and 26% of primary intracranial tumors. They are most common in middle-aged and elderly patients. The female to male ratio is approximately 3:2. Meningiomas have a wide range of histopathological appearances. Some histologic variants show low risk of recurrence and aggressive growth and these include the meningothelial, fibrous, transitional, psammomatous, angiomatous, microcystic, secretory, lymphoplasmacytic and metaplastic subtypes. Other meningiomas show greater likelihood of recurrence and/or aggressive behavior and these include atypical, clear cell, choroids, rhabdoid, papillary and anaplastic subtypes [WHO 2000].
Secretory meningioma is a relatively rare histological subtype. The hallmark is the presence of focal epithelial proliferation, in the form of intracellular eosinophilic material. These round-to-oval hyaline bodies are also referred to as pseudopsammoma bodies. They show positive staining for periodic acid Schiff with or without diastase. Ultrastructurally, they are composed of filamentous and granular material located predominantly in intracellular lamina lined by microvilli. [Nishio, 2001]
Secretory meningioma is reported to represent 3% of meningiomas with a female to male ratio of 9:1. [Probst-Cousin, 1997]. The Immunophenotype of the focal epithelial differentiation in secretory meningioma is CEA-, EMA- and CK7-positive but CK20-negative [Assi, 1999] . Despite its distinct morphologic features, the biologic behavior of secretory meningioma is reported to correspond to those of meningioma in general [Nishio, 2001]
Contributed by Muammar Arida, MD