Hairy cell leukemia variant: a morphologic, immunologic and clinical study of 7 cases.

Hairy cell leukemia (HCL), a well-recognized chronic lymphoproliferative disorder, is frequently characterized by pancytopenia, monocytopenia, splenomegaly and marrow fibrosis, which typically leads to an unsuccessful bone marrow aspiration (dry tap). Patients with a high white cell count without neutropenia and/or monocytopenia, with an aspirable and hypercellular marrow, splenomegaly and neoplastic cells with hairy cell features have been recently recognized and classified as HCL variants. We report here the clinical, hematological and immunological features of 7 such cases. All patients presented splenomegaly with a high leukocyte count; 2 were anemic and only 1 thrombocytopenic. Five patients were treated with alpha-Interferon (alpha-IFN) but 4 failed to achieve any significant response; two of these were subsequently splenectomized and successfully treated with Chlorambucil. Splenectomy, followed by Chlorambucil, was performed at diagnosis in the remaining 2 cases, both of which achieved a partial response and are alive and well. Six out of the 7 patients are still alive. The recognition of these peculiar patients is also important because they most often do not respond to alpha-IFN, while splenectomy, followed by Chlorambucil, may be a reasonable therapeutic option for them.