Cytology of microcystic meningioma in crush preparation.

Microcystic meningioma is a rare variant of meningioma, showing microcystic formations throughout the tumor. To the best of our knowledge, there have been no reports describing cytologic findings of microcystic meningioma. Our case was a 66-yr-old woman with a tumor mass adhered to the dura matter. The crush preparations of a small tissue fragment resected from the mass showed medium- to large-sized, well-cohesive clusters or sheets of uniform tumor cells. The tumor cells did not show a feathering-off pattern. Various-sized cystic spaces were observed within the clusters and sheets. The cytoplasm was relatively abundant, and the nuclear:cytoplasmic ratio was lower than that of classic meningioma. We believe that the cystic spaces within the cell clusters or sheets are characteristic of microcystic meningioma. The cytology of microcystic meningioma seen in our case was similar to that of metastatic adenocarcinoma, but relatively monotonous bland cells, smooth nuclear outline, and inconspicuous nucleoli led us to the diagnosis of meningioma rather than adenocarcinoma. Copyright 2000 Wiley-Liss, Inc.