Findings from positron emission tomography and genetic analyses for cerebellar liponeurocytoma.

Cerebellar liponeurocytoma is a rare tumor that usually develops in adult patients, and is categorized as World Health Organization grade II. Because of the small number of reports on its radiological and pathological features, the disease remains poorly characterized. The current case involved a 59-year-old man with tumor in the upper cerebellar vermis. Preoperative positron emission tomography (PET) showed high uptake on (11)C-methionine PET, but low uptake on (18)F-fluorodeoxyglucose PET. These findings resemble those of central neurocytoma and oligodendroglioma, but are incompatible with other brain tumors. Subtotal tumor removal was performed by suboccipital craniotomy. Histopathological examinations showed sheets of small, isomorphic cells with round nuclei and clear cytoplasm, and focal vacuolated cells resembling adipose cells. On immunohistochemistry, tumor cells were positive for synaptophysin and NeuN. Vacuolated cells were immunoreactive for perilipin. Based on these findings, cerebellar liponeurocytoma was diagnosed. Genetic analyses revealed absences of both chromosome 1p/19q loss and isocitrate dehydrogenase 1 mutation, further ruling out oligodendroglioma. These radiological and genetic aspects of cerebellar liponeurocytoma, which are mostly in common with central neurocytoma, should prove helpful in differentiating this rare tumor from other tumors with similar morphology.