Cytodiagnosis of meningioma with atypical cytologic features.

The atypical cytomorphologic features present in intraoperative cytologic samples from two cases of meningioma are described. The important atypical cytologic features were slight nuclear hyperchromasia, cellular pleomorphism, anisokaryosis, frequent mitotic figures, nuclear grooves, occasional binucleations and a few intranuclear inclusions. The imprint smears from the case of atypical meningioma were cytologically diagnosed as showing atypical meningioma or sarcoma. The fine needle aspiration smears from the case histologically diagnosed as an angioblastic meningioma (meningeal hemangiopericytoma) showed more nuclear hyperchromasia and pleomorphism and were cytologically diagnosed as showing malignant meningioma. Atypical cytologic features in meningiomas may cause cytodiagnostic difficulties since other primary and metastatic meningeal tumors may show similar features; the main differential diagnostic possibilities are discussed.