CYTOGENETIC ABERRATIONS IN 188 BENIGN AND BORDERLINE ADIPOSE-TISSUE TUMORS

Chromosome studies of lipomas have revealed an extensive cytogenetic h eterogeneity. To investigate the frequencies of previously recognized cytogenetic subgroups and to find out if more recurrent rearrangements can be identified, we have analyzed cytogenetically short-term tissue cultures of 237 samples from 188 adipose tissue tumors obtained from 142 patients. Only one of 58 tumors from 18 patients with multiple lip omas (more than two tumors) had karyotypic changes. Among the sporadic lipomas, 20 tumors had supernumerary ring chromosomes of unknown orig in, 55 had different aberrations involving chromosome segment 12q13-15 , 11 had changes of 6p or chromosome 13, but no rings or 12q13-15 chan ges, and-14 had various other aberrations. Ring chromosomes were found in all cytogenetically abnormal lipomas histologically classified as atypical and in nine tumors classified as typical lipoma or spindle ce ll lipoma. Recombinations between 12q13-15 and a few other bands or se gments were seen more than once: 3q27-28 (15 tumors), 2p22-24 and 2q35 (four tumors), 1p32-34 and 13q12-14 (three tumors), and 5q33 (two tum ors). Recombinations of 12q13-15 with 2q35 and 13q12-14 have not been described before. Of eight tumors with chromosome 13 aberrations, five had loss of 13q material. Aberrations of 12q13-15, 6p, and/or chromos ome 13 were found simultaneously in nine tumors. Two to four samples f rom the same tumor were investigated in 29 tumors with clonal aberrati ons. Thirteen of these tumors displayed clonal evolution; also noted i n another 17 tumors in which only one sample had been investigated. Th us clonal evolution occurred in 30% of the tumors and was particularly frequent in atypical lipomas. (C) 1994 Wiley-Liss, Inc.