A case of malignant mastocytosis with near-haploid, near-diploid, and polyploid cells in the bone marrow.

Chromosome analysis in bone marrow cells of a 41-year-old woman with malignant mastocytosis (MM) revealed near-haploid (59%), near-diploid (36%), and polyploid (5%) cells. Near-haploid cells had a mode of 25 chromosomes with variable disomy and nullisomy of particular chromosomes. Disomy for chromosome 19 and chromosome 20 were most common. A 17p+ marker was observed in all cells. Other structural chromosomal changes were dicentrics, ring chromosomes, translocations, and double minutes. The modal chromosome number in near-diploid cells was 46 with a range of 41-52. The majority of cells with 46 chromosomes were pseudodiploid and only a few had a normal female karyotype. As in near-haploid cells, various structural chromosomal changes were found. The 17p+ marker was also present in occasional cells suggesting a relationship between the two tumor cell populations. Chromosome numbers in polyploid cells ranged from 70 to about 600. Identical copies of dicentrics or markers were identified in some cells.