Medullocytoma (lipidized medulloblastoma). A cerebellar neoplasm of adults with favorable prognosis.

This study describes three cases of neuroectodermal cerebellar neoplasms occurring in adults, characterized by a monomorphic population of round cells with scanty cytoplasm and focal areas of lipid accumulation. Astrocytic and neuronal differentiation was confirmed in these cells by glial fibrillary acidic protein and synaptophysin immunoreactivity. Electron microscopy performed in two cases showed neuritic processes, synapses, and dense-core granules. Patients included two men and one woman, and the age at diagnosis was 36, 37, and 57 years, respectively. Two patients refused any postoperative treatment. One of these had two surgically removed recurrences after 10 and 11 years and died postoperatively from intracranial hemorrhage. The second had two recurrences after 10 and 15 years and is alive and in good health at the last follow-up. The third patient received postoperative radiotherapy and is alive and well after 2 years. Review of the literature revealed seven cases of cerebellar neoplasms with histological features similar to those observed in our series. These lesions have been considered a variant of medulloblastomas. The age of patients ranged from 42 to 77 years (mean age, 51 years); four were women, 3 men. Follow-up information available in two cases indicates a 5-year survival with surgery alone. These data indicate that these cerebellar neuroectodermal neoplasms have morphologically unique features and indolent biologic behavior that distinguish them from the highly aggressive medulloblastoma; the term medullocytoma for this form is suggested.