Cytodiagnosis of pilocytic astrocytoma in smear preparations

OBJECTIVE: To assess the cytologic features in smear preparations of 23 pilocytic astrocytomas. STUDY DESIGN: Examination of 23 smears. RESULTS: In all cases, the diagnosis was subsequently confirmed on histologic sections. The smears were moderately cellular, with a variably myxoid background. They showed bipolar "hair" cells with elongated, coarse cytoplasmic processes; bland, oval nuclei; Rosenthal fibers; eosinophilic granular bodies; and hyalinized vessels. Stellate cells and bare tumor nuclei were also present. Nuclear pleomorphism, vascular proliferation, perivascular pseudorosettes, microcalcification and hemosiderin-laden macrophages were infrequent features. Mitoses and necrosis were absent. The differential diagnosis should include diffuse fibrillary astrocytomas of all histologic grades, pleomorphic xanthoastrocytoma, ganglion cell tumor, ependymoma and reactive gliosis. CONCLUSION: Correlation of cytologic features with clinical and radiologic information allows pilocytic astrocytoma to be distinguished from other conditions.