Cytogenetic evaluation of isochromosome 17q in posterior fossa tumors of children and correlation with clinical outcome in medulloblastoma. Detection of a novel chromosomal abnormality.

Background: A number of chromosomal abnormalities have been described in the presence of central nervous system tumors; isochromosome 17q, representing a loss of heterozygosity for the short arm of the chromosome 17, is the one most frequently reported in association with medulloblastoma. The purpose of this study was to evaluate the prognostic correlation of this variable, compared with other variables (surgery extent and radiotherapy), with survival.

Methods And Results: We looked for the presence of i(17q) in 32 children affected by posterior fossa tumors, including 16 medulloblastomas and 2 teratoid/rhabdoid tumors.