Polyploidy of the bone marrow.

In a consecutive series of 841 patients whose bone marrows were cytogenetically investigated because of verified or suspected haematological disease, 11 patients were found to have at least 10% polyploid bone marrow mitoses. The chromosome numbers varied greatly between the cells of the same patients and between the patients. In 4 cases, the number was nearly or exactly tetraploid and in 1 patient a prevalent octaploid line was seen. Structurally abnormal marker chromosomes were seen in 8 of the patients. A total of 31 bone marrow chromosome counts were performed on a young woman with acute myelomonocytic leukaemia who had had several drug-induced remissions during the 3 1/2 years of disease. The results were related to the clinical findings. On several occasions a clear-cut correlation was noted between high proportions (nearly 100%) of polyploid cells and relapse on the one hand and low proportions (as low as 0%) of polyploids and remission on the other. Of the 11 patients, 2 had chronic myeloid leukaemia, 3 acute myelomonocytic leukaemia, 3 acute myeloid leukaemia and a further 3 some other malignant haematological disorders. We conclude that polyploidy is a feature associated with rare cases of leukaemia and other malignant diseases. It is often a sign of a poor prognosis.