A RECURRENT CEREBELLAR LESION IN A YOUNG BOY

摘要

A 7-year-old boy originally presented wfkh a cerebellar lesion. The magnetic resonance imaging demo'nstrated a complex posterior fossa mass with predominantly Tl darkness and a nidus of enhancement (Figure 1). The mass was impinging upon the posterior aspect of the fourth ventricle. This original resection was followed by a second resection approximately 2 years later, and a third resection approximately 4 years after the first resection.In the original resection specimen (Figure'2), this neoplasm is-characterized by a monomorphic population of small round cellswith dispersed chromatin. There are many acellular neuropil-rich formations. Mitotic figures, microvascular proliferation and necrosis are not seen. Rosenthal fibers, eosinophilic granular bodies and a biphasic appearance are not identified. The tumor cells are positive for synaptophysin (Figure 3) and negative for glial fibrillary acidic protein (GFAP; Figure 4). In the most recent resection specimen, the tumor has similar morphology (Figure 5), and the rumor cells are positive for synaptophysin (Figure 6) and S-100, but negative for Neu-N, neurofilament protein, epithelial membrane antigen, chromogranin and GFAP (Figure 7). The Ki67 labeling index is 1 %.