Chromosome 12 breakpoints are cytogenetically different in benign and malignant lipogenic tumors: localization of breakpoints in lipoma to 12q15 and in myxoid liposarcoma to 12q13.3.

ABSTRACT

Cytogenetic study of short-term cultures from 10 adipose tissue tumors (eight lipomas, one myxoid liposarcoma, and one mixed liposarcoma) have revealed clonal chromosome abnormalities in seven cases. In both malignant tumors, translocation (12;16) was the sole aberration, and in the mixed liposarcoma, the breakpoints could be sublocalized to bands 12q13.3 and 16p11.2, thus confirming findings of Eneroth et al., Cancer Genet. Cytogenet., 48 101-107, 1990. Three lipomas displayed predominantly normal karyotypes; in a fourth case, the karyotype 44,XX,-6,der (7)t(6;7)(p21.3-22;p22)ins(7)(p22q11.2q22),-13 was found. Four remaining lipomas were characterized by structural rearrangements of chromosome 12. We were able to achieve high resolution banding patterns in two tumors with translocations (3;12)(q28;q15) and (1;2;12)(p36.;q13;q15). In both of these cases, the chromosome 12 breakpoint could be unequivocally assigned to band q15. Similarly, band 12q15 was also rearranged in two other lipomas with translocations (12;14)(q15;q32) and (12;20)(q15;q13.1). Our results support the hypothesis that the chromosome 12 breakpoint in lipomas is located more distally than the breakpoint in myxoid liposarcomas and some other soft-tissue malignant neoplasms and that it is cytogenetically identical with breakpoints detected in such benign tumors as uterine leiomyoma and pleomorphic adenoma of the salivary gland.