[The karyotype of bone marrow cells in the preleukemic phase of chronic myelocytic leukemia]

The caryotype of bone-marrow cells of 19 patients affected with leukocytosis of obscure origin was examined by means of G-staining. A chronic myelogenous leukaemia in its preleukaemic stage was diagnosed in 11 patients by identifying Ph'-chromosomes in all metaphases observed and a lowered acid leukocyte phosphatase. Besides Ph'-chromosomes an aneuploida (47 chromosomes with trisomia 8) was observed in one patient. The diagnostic and prognostic significance of this pathological caryotype is discussed.