Cytogenetic findings in five patients with hairy cell leukemia.

We studied five cases of hairy cell leukemia (HCL) using conventional cytogenetics. All patients were diagnosed with typical HCL. Chromosome analysis was carried out on a 72-hour culture of peripheral blood. Phytohemagglutinin (PHA) mitogen was used. Clonal chromosome abnormalities were found in 2/5 patients (40%), a complex abnormality being identified in one of them. The chromosomes involved were: 1, 6, 7, 8, and 17. No patient showed trisomy 12 or a 14q+. An interesting result was the finding of del(7)(q32) as a sole anomaly.