Cytologic Features of Secretory Meningioma in Squash Preparation

Secretory meningioma is a distinct subtype of meningioma. We describe the cytologic features of a secretory meningioma on squash preparations, in comparision with other cytologic mimickers. A 54-year-old woman presented with hearing loss, vertigo, tinnitus, and headache for seven years. A brain MRI study revealed a 4.5 cm sized mass in the cerebellopontine angle, which showed homogenous signal intensity in T2-weighted image. The intraoperative squash smear showed some well-defined, thin rimmed intracytoplasmic inclusions, containing a finely granular eosinophilic core among less cohesive meningiomatous cells. Histologic sections revealed a meningothelial meningioma with scattered inclusions, with periodic acid-Schiff, carcinoembryonic antigen, and cytokeratin positivity. Identification of characteristic intracytoplasmic inclusions is helpful for diagnosing secretory meningiomas. On squash preparations, differential diagnoses included tumors with inclusions or cytoplasmic vacuolizations, such as metastatic mammary infiltrating ductal carcinoma, gastric adenocarcinoma, hepatocellular carcinoma, and clear cell ependymoma, oligodendroglioma, hemangioblastoma, chordoma, and other variants of meningiomas (clear cell, xanthomatous, microcytic, and chordoid variants). In addition, the possibilities of glioma with eosinophilic granular body, and metastatic tumors from mammary infiltrating ductal carcinoma, gastric adenocarcinoma, and hepatocellular carcinoma in meningioma should be considered.ope