A clinicopathologic and immunohistochemical analysis of 53 cases of medulloblastoma with emphasis on synaptophysin expression.

Synaptophysin (SYN) has been identified as an integral membrane glycoprotein of presynaptic vesicles in neurons and neuroendocrine cells, and as a marker for medulloblastoma and other neuronal tumors. SYN expression was studied with a monoclonal antibody (MAb) by the immunoperoxidase technique in 53 medulloblastomas. The expression of neuron-specific enolase (NSE), Leu-7 (LEU), S-100 protein (S100), glial fibrillary acidic protein (GFAP), neurofilament protein (NF), vimentin (VIM), cytokeratin (CKER), and desmin (DES) was also assessed with antisera and MAbs. SYN reactivity was present in 94% of tumors, whereas reactivity with other markers of neuronal differentiation was also observed: NSE (100%) and LEU (83%). Regarding the intermediate filament proteins, 38% of the cases were reactive for VIM, 21% for GFAP, and 9% for DES; none expressed NF or CKER. Eight percent were reactive for S100. Among the 53 cases, the male-female ratio was 1:3; 80% of DES-positive tumors occurred in females. The mean age was 10.5 yr, (60% diagnosed in the first decade; peak age incidence between 5 and 10 yr). Five tumors were discovered in patients older than 20 yr of age. Follow-up showed that 40% of patients developed a recurrence and 47% of patients died of tumor. No statistically significant relationship was demonstrated between patterns of immunoreactivity and prognosis. We conclude that SYN is a useful marker for medulloblastomas, indicating that this tumor is a primitive neuronal-neuroblastic neoplasm. However, it is but one of several immunophenotypic markers expressed by the medulloblastoma.