Abstract
Background : Pineal parenchymal tumor of intermediate differentiation (PPTIDs) are rare brain tumor, and there are few cytological reports about this tumor. We report herein on a case of PPTID diagnosed on squash cytology.
Case : A woman in her 60’s visited a nearby hospital complaining of headache. A mass was found in the pineal body with magnetic resonance imaging and she underwent an operation at Kurume University Hospital. Squash cytological smears showed a loose cluster of tumor cells with bland cytological findings against the neuropil background. Individual tumor cells showed coarse to granular chromatin, like that seen in neuroendocrine tumors. On immunocytochemistry, Ki67 labeling index was observed in 5% of the tumor cells. Histologically, the tumor showed a monotonous appearance with scant cytoplasm. No distinct necrosis or mitosis was seen, whereas an increase of cellularity was observed. On immunohistochemistry the tumor cells were positive for neurofilament, and Ki67 labeling index was observed in 4% of the tumor cells.
Conclusion : Cytological findings of PPTID were characterized by coarse chromatin and the neuropil background. It is important for accurate diagnosis of PPTID to identify the Ki67 labeling index based on the characteristic cytological findings.
