DUPLICATION OF CHROMOSOME SEGMENT 12Q15-24 IS ASSOCIATED WITH ATYPICAL LIPOMATOUS TUMORS - A REPORT OF THE CHAMP COLLABORATIVE STUDY-GROUP

Ordinary lipomas are cytogenetically characterized by a variety of bal anced rearrangements involving chromosome segment 12q13-15, and atypic al lipomatous tumors (ALT) by supernumerary ring chromosomes or giant markers known to contain amplified 12q sequences. In a series of 228 c ytogenetically analyzed and histopathologically reexamined ordinary li pomas and ALT, 10 tumors showed unbalanced chromesome-12 aberrations. All 4 tumors with loss of segments from 12q were classified as ordinar y lipomas, whereas 5 of the 6 tumors showing gain of 12q material were diagnosed as ALT. One or three extra copies of 12q15-q24 were present in all 5 ALT. We conclude that duplication of 12q sequences may be a sufficient level of amplification for development of the microscopic a ppearance that characterizes ALT. (C) 1996 Wiley-Liss, Inc.