Cytologic Characteristics of Intracytoplasmic Refractile Eosinophilic Granular Bodies in Anaplastic Oligodendroglioma

BACKGROUND: Oligodendrogliomas, which have a relatively better prognosis than tumors of the astrocytic lineage, have few morphologic clues for diagnosis. CASE: To address this problem, eosinophilic refractile inclusions were examined cytologically in the tumor of a 59-year-old man, using surgical materials for rapid diagnosis. Cytologic, histologic, and immunohistochemical findings were compatible with the refractile eosinophilic inclusions found in oligodendroglial tumors. The tumor cells presented a sheet-like epithelial pattern, forming no overlapping cell clusters, with an ill-defined cytoplasmic membrane, and nuclei that appeared to be naked, approximately 2 times the size of a red blood cell (approximately 7 microm) in diameter. It was easier to examine the cells and inclusions by cytologic preparations than by histology. CONCLUSION: The inclusions were thought to be a diagnostic clue for oligodendrogliomas, especially on cytology, and cytology was more useful than histology.