Spatial variability of genomic aberrations in a large glioblastoma resection specimen

In the present study, the distribution of genetic aberrations in a glioblas toma resection specimen of unusually large size (9x8x2 cm) was investigated using comparative genomic hybridization (CGH). CGH was performed on 20 sam ples taken from the specimen, and the genetic aberrations found were compar ed with the regional histology. The samples were histopathologically graded according to WHO criteria, and a division in high- and low-grade areas and infiltration rims was made. In high-grade areas, low-grade areas as well a s infiltration rims, gains on 10q11.2-pter (14/20), 11q12-q22 (6/20) and lo sses on 4q13-qter (9/20), 10q22-qter (8/20), 11p14-pter (5/20), 13q12-qter (7/20) were revealed. Gains on 1q21-32 (2/4) and losses on 7p21-pter (3/4) were exclusively found in the high-grade areas. In the low-grade tumor samp les and in the infiltration rim, gains on 16p11.2-pter (6/16), 17p11.2-pter (6/16), 17q11.2-qter (5/16), 20q11.2-q13 (3/16) and deletions on 5q31-qter (4/16) were detected. Gains on 7q21-qter (8/11) and 8q11.2-qter (6/11), an d loss of chromosome 9 (4/11) and the Y-chromosome (4/11) were found in the high-grade and low-grade samples, not in the infiltration rims. The findin g of a set of identical chromosomal aberrations throughout the resection sp ecimen, most of which have been previously reported in gliomas, confirms a mechanism of clonal tumor proliferation operative in gliomas. The previousl y unreported genetic alterations which were predominantly traced in the tum or rims, might reflect either selection for properties related to infiltrat ing behavior, or genomic instability of subclones. The findings illustrate the importance of searching for high-grade genetic aberrations in low-grade tumor samples taken from cases in which sampling error is suspected.