Cytogenetic studies in chronic lymphocytic leukemia, prolymphocytic leukemia and hairy cell leukemia: a progress report.

We studied the B lymphocyte metaphases in 78 of 94 cases of CLL, 24 of our 28 hairy cell leukaemias, 4 CLL's which transformed into prolymphocytic leukaemia and 8 original prolymphocytic leukaemias. Twelve CLL's were carriers of trisomy 12, 13 of this trisomy 12 with other abnormalities and 15 had other abnormalities without trisomy 12. Trisomy 12 seemed to be more frequent in patients with CLL or prolymphocytic leukaemia with a monoclonal gammopathy. In contrast to our previous results, the isolated finding of a trisomy 12 had an influence on the median survival.