An immunohistochemical analysis of medulloblastoma and PNET with emphasis on N-myc protein expression

Medulloblastoma is the most common primitive neuroectodermal tumor (PNET) of the central nervous system. Standard whole neuroaxis radiation prolongs survival, but causes mental retardation and growth disturbance. It is important to find appropriate prognostic indicators for medulloblastoma in children. We assessed the prognostic values of N-myc expression in medulloblastoma. Nineteen medulloblastoma or supratentorial PNET (SPNET) patients (15 males and 4 females) were immunohistochemically investigated for N-myc expression. Sixteen patients were N-myc-positive, and three were N-myc-negative. N-myc-positive patients had a tendency towards a poor outcome (P = 0.1125). N-myc-negative tumors were more differentiated towards glial lineage than N-myc-positive tumors. N-myc-negative and GFAP-positive patients (n = 2) tended to survive N-myc-positive and GFAP-negative patients (n = 13). In medulloblastoma and SPNET patients, N-myc expression may become an appropriate indicator of poor prognosis and primitive cell differentiation.