Context: Hairy cell leukemia HCL is a rare, low grade, B-cell neoplasm with a characteristic morphologic and immunophenotypic profile. It has to be distinguished from chronic lymphoproliferative disorders because of different treatment protocol and clinical course. Aims: To evaluate clinicopathological features including immunophenotypic analysis of cases diagnosed as HCL. Materials and Methods: The present study included 28 cases diagnosed over a period of nine years Clinical presentation, complete blood count, bone marrow aspirate, and flow cytometric analysis of cases were reviewed.
Hairy cell leukemia is an uncommon hematological malignancy characterized by an accumulation of abnormal B lymphocytes. Hairy cell leukemia was originally described as histiocytic leukemia, malignant reticulosis, or lymphoid myelofibrosis in publications dating back to the s. The disease was formally named leukemic reticuloendotheliosis and its characterization significantly advanced by Bertha Bouroncle and colleagues at The Ohio State University College of Medicine in Its common name, which was coined in ,  is derived from the "hairy" appearance of the malignant B cells under a microscope.
Diagnosis of hairy cell leukemia by flow cytometry.
This disease is rare, with fewer than 1 in 10, people being diagnosed with HCL during their lives. Although most patients are white males over the age of 50, it has been diagnosed in at least one teenager. Men are four to five times more likely to develop hairy cell leukemia than women. It does not appear to be hereditary, although occasional familial cases have been reported, usually showing a common HLA type. The cause is unknown, but, in general, believed not to be caused by tobacco, ionizing radiation, pesticides, or industrial chemicals other than possibly diesel.
The diagnosis of hairy cell leukemia HCL has traditionally been based on microscopic means. Immunophenotypic analysis of peripheral blood by flow cytometry is not widely recognized as a method for diagnosing HCL, perhaps due to the expectation of low yield of neoplastic cells in patients who are characteristically leukopenic. We wished to determine if this pattern was valuable in the diagnosis of HCL in leukopenic patients with low levels of neoplastic cells in the peripheral blood. The abnormal immunophenotype above was observed in 25 peripheral blood specimens from patients with unexplained cytopenias or suspected lymphoproliferative processes.