Clear-cell meningioma: diagnosis by fine-needle aspiration biopsy.

Clear-cell meningiomas have a more aggressive behavior than other meningioma subtypes and the cytologic features of clear-cell meningioma have not been described. A fine-needle aspiration biopsy (FNAB) of a sacral clear-cell meningioma was performed in a 28-yr-old woman. This tumor was a metastasis from a posterior fossa meningioma that had been unresectable, but had been present for 7 yr. Cytologically, clear-cell meningiomas have a whorled, syncytial architecture and spindled to polygonal, bland-appearing nuclei. In contrast to the more classic meningioma, the clear-cell variety has vacuolated cytoplasm. The differential diagnosis includes a number of other neoplastic processes. Separation of clear-cell meningioma from these other entities may be difficult because of its rather unusual cytoplasmic features and its occurrence in unusual sites.