IS MEDULLOBLASTOMA THE SAME TUMOR IN CHILDREN AND ADULTS

The appearance of medulloblastoma in adult age and the uncertain overl apping of prognostic factors in pediatric and adult populations stimul ate the question of whether medulloblastoma is different in adults and in children. The pathologic features, proliferation potential and gli al/neuronal differentiation have been investigated in 42 adult medullo blastomas and 42 medulloblastomas of children; the quantitative data h ave been compared between the two groups of age. Homer-Wright rosettes , nuclear polymorphism and histologic signs of neuronal differentiatio n were more frequent in children cases; GFAP-positive tumor cells and desmoplastic type were more frequent in adult cases. The mean, median and rage of LIs, with PCNA and MIB-1 were significantly (p < 0.05) hig her in adults than in children. All cases, independently from age of t he patients were immunoreactive with markers of neuronal commitment (c lass III beta tubulin isotype, MAP-2, neurofilaments). The immunoreact ivity pattern suggested a more mature neuronal character in desmoplast ic cases of adults than of children and in classic cases of children t han of adults. In conclusion, some phenotypic differences between chil dhood and adult medulloblastoma exist, but do not support a substantia lly different course of the disease. The higher proliferation potentia l in adult than in childhood cases is unexpected in a tumor of embryon al origin, and reduces the applicability of Collin's law to medullobla stoma.