UNUSUAL CEREBELLAR GANGLIOGLIOMA WITH MARKED CYTOLOGIC ATYPIA

Neuronal differentiation is well documented in cerebellar primitive ne uroectodermal tumors but is uncommon in other cerebellar neoplasms. Al though rare, gangliogliomas and gangliocytomas have been previously de scribed in the cerebellum. We report a cerebellar ganglioglioma in a 1 4-year-old boy, which revealed bizzare markedly pleomorphic cells with extremely pronounced nuclear atypia but less than one mitosis per 50 high-power fields and no necrosis. The tumor showed glial as well as n euronal differentiation, with abundant bi- and multinucleated ganglion cells. There were abundant Rosenthal fibers, eosinophilic granular bo dies, focal calcification, and perivascular lymphocytic infiltrates. T here has been no evidence of tumor recurrence or neurological deterior ation 21 years after surgery, although the narked nuclear atypia led t o an initial diagnosis of an anaplastic glioma. We stress the need for careful evaluation of cerebellar gliomas in children that show only n uclear atypia or endothelial hyperplasia in the absence of other featu res of malignant.