[Chromosome 11 abnormality in a case of acute monocytic leukemia (M5b)].

The authors report the case of a 25 year old man with a differentiated (M5 b) acute monocytic leukaemia resistant to polychemotherapy. The patient died four months after the onset of the disease. Cytogenic studies showed thickening of the long arm of chromosome 11, an abnormality considered until now to be specific for poorly differentiated (M5 a) acute monocytic leukaemias.