Chromosomal abnormalities in 47 pediatric brain tumors.

The karyotypes of 47 pediatric brain tumors (14 cerebellar pilocytic astrocytomas, six cerebral pilocytic astrocytomas, seven anaplastic astrocytomas and glioblastomas, nine medulloblastomas [PNETs], one cerebral neuroblastoma, four ependymomas, and seven miscellaneous other neoplasms) are presented. Most of the pilocytic astrocytomas and ependymomas had normal karyotypes. In contrast, the majority of the anaplastic astrocytomas-glioblastomas were abnormal. The abnormalities included losses and structural abnormalities of chromosomes 9, 13, and 17, and double minutes. There were no losses of chromosomes 10 and 19q or gains of chromosome 7, which are among the most common abnormalities of adult glioblastomas. The chromosomal abnormalities in the medulloblastomas were similar to those reported in the literature but less frequent. Four tumors (choroid plexus papilloma, meningioma, cerebral malignant rhabdoid tumor, and immature teratoma) had losses of chromosome 22.