A well-differentiated liposarcoma with a new type of chromosome 12-derivedmarkers

Well-differentiated liposarcomas (WDLPS) are cytogenetically characterized by the presence of supernumerary ring or giant rod marker chromosomes. Thes e supernumerary chromosomes are composed of amplified sequences from chromo some 12 (12q14 similar to 15) in association with amplified segments from v arious other chromosomes, and contain alterations of the alpha satellite se quences. We report a case of WDLPS of the lipoma-like and sclerosing subtyp e that contains a novel type of supernumerary marker chromosome. Instead of rings or giant rods, these cells had three apparently identical copies of a subtelocentric supernumerary marker with a size and shape similar to C-gr oup chromosomes. Fluorescence in situ hybridization analysis revealed that the markers were composed of amplified material from 12q14 similar to 15, i ncluding the genes MDM2 and CDK4. Similar to the rings and giant rods obser ved in other WDLPS cases, these unusual markers had no alpha satellite repe ats at the primary constriction site, but centromeric activity could be dem onstrated by using anti-centromere protein C antibodies. These findings sho w that the supernumerary markers of WDLPS may be variable in size and shape , but consistently share the same genomic structure, specifically 12q ampli fied sequences together with centromere alterations, and underline the impo rtance of molecular methods in the diagnosis of adipose tissue tumors. (C) 2001 Elsevier Science Inc. All rights reserved.