De novo hairy cell leukemia with a major BCR/ABL1 rearrangement: A case report with a literature review

Abstract

Hairy cell leukemia (HCL) is a very rare mature B-cell neoplasm and its simultaneous occurrence with chronic myeloid leukemia has been reported in only three cases. The pathogenesis and relationship of the two diseases are not clear. Here we report a case of HCL expressing a BCR/ABL1 clone, which showed molecular remission of the fusion clones and achieved partial remission over nine months of cladribine therapy. After a thorough analysis of previous studies and the results of this patient, we speculate that a subclone evolved to have an additional genetic BCR/ABL1 rearrangement. We also review all published literature on HCL with BCR/ABL1 rearrangement and discuss the pathophysiology of these unusual cases.