Cytogenetics of chronic myelomonocytic leukemia.

In a retrospective multicenter study by the Groupe Français de Cytogénétique Hématologique, chromosome investigation was undertaken in 120 cases of chronic myelomonocytic leukemia, which was diagnosed in accordance with the French-American-British (FAB) criteria. Chromosome abnormalities of the clonal type were present at diagnosis in 30% of the patients. Median age of these patients was lower than for these without karyotypic abnormalities, and prognosis was less favorable. The most frequently encountered characteristic chromosome change was monosomy 7; chronic myelomonocytic leukemia (CMLL) with monosomy 7 occurs in younger age groups and has a very poor prognosis. Next in frequency were trisomy 8, iso(17q), and a 12p anomaly. The latter may have to be classified among the so-called primary characteristic chromosome changes in leukemia. All chromosome changes were of the type usually found in myeloid proliferation, and no anomaly specific for CMML was discovered. Isochromosome 17q was found only during blastic phase. Several of the CMML cases with chromosome anomalies were secondary leukemias, and among these was one case with a homogeneously staining region (HSR), which is rarely reported in leukemia. A paraproteinemia was found in 12% of the patients. No correlation of its occurrence with presence or type of karyotypic anomaly could be found.