COMPARISON OF CHROMOSOME-ABERRATIONS IN LEIOMYOMA AND LEIOMYOSARCOMA USING FISH ON ARCHIVAL TISSUES

Fluorescence in situ hybridization (FISH) with chromosome-specific pro bes was used to study cytogenetic changes in five cases of leiomyosarc oma (LMS) and nine cases of uterine leiomyoma (LM). Biotinylated DNA p robes for the centromeric regions of chromosomes 1, 6, 8, 9, 17, and 1 8, painting probes for chromosomes 1 and aa, and the cosmid probe for chromosome region 21q22.3 were used on nuclei isolated from paraffin b locks. Four of five LMS cases revealed major chromosomal aberrations, while the only case with minor clonal aberrations was subsequently fou nd not to be a typical LMS. The most common numerical aberrations foun d in the LMS cases were extra copies of chromosome 8 (three of five ca ses), loss of chromosome 1 (three of five cases), and loss of chromoso me 6 (two of five cases). One of two LMS cases studied with a chromoso me 1 painting probe demonstrated translocations of chromosome 1. In co ntrast to LMS, only five of nine uterine LM cases had abnormal clones, and these were smaller than those in LMS. Two LM cases showed 9% tetr asomy 8 with 17 or 20% monosomy 6, and three other cases had monosomy 6 clones in 18-34% of cells. These results indicate that typical LMS i s characterized by multiple chromosomal aberrations affecting most of the cells, whereas borderline LMS and LM have fewer affected chromosom es and less clonal involvement.