Chromosome abnormalities in patients with hairy cell leukemia

We evaluated chromosomes from 20 patients with hairy cell leukemia (HCL) to ascertain the frequency and type of consistent chromosomal abnormalities. Samples from 17 patients were obtained from peripheral blood cultures grown 24 and 48 hours without phytohemagglutinin, or from bone marrow samples. Two male patients had similar, consistent abnormalities; one patient's karyotype was 46,X,+12; that of the second was 46,X,+C marker. In the latter case, the distal long arm of the C marker most closely resembled chromosome No. 12 from band q14 to q terminal, but the short arm and proximal long arm were of undetermined origin. Both karyotypes lacked the Y chromosome. A third patient had, in one sample, a single abnormal cell with an extra No. 3 and an extra No. 12 (48,XY,+3,+12), and in a later sample, a second cell of poor morphology which also could have been trisomic for no. 12. The two patients with consistent chromosome abnormalities had rapidly progressive disease and a relatively short clinical course from the time of diagnosis (5 and 7 months, respectively). Further data are needed, but the results thus far suggest that patients with consistent chromosome abnormalities could be considered as candidates for aggressive combination chemotherapy.