Leukemic cells may gather in the spleen and cause it to swell; this can have the side effect of making the person feel full even when he or she has not eaten much.Hairy cell leukemia is commonly diagnosed after a routine blood count shows unexpectedly low numbers of one or more kinds of normal blood cells, or after unexplained bruises or recurrent infections in an otherwise apparently healthy patient.Platelet function may be somewhat impaired in HCL patients, although this does not appear to have any significant practical effect. It may result in somewhat more mild bruises than would otherwise be expected for a given platelet count or a mildly increased bleeding time for a minor cut, likely the result of producing slightly abnormal platelets in the overstressed bone marrow tissue. Patients with a high tumor burden may also have somewhat reduced levels of cholesterol, especially in patients with an enlarged spleen. Cholesterol levels return to more normal values with successful treatment of HCL. Cause
As with many cancers, the cause of HCL is unknown. Exposure to tobacco smoke, ionizing radiation, or industrial chemicals (with the possible exception of diesel) does not appear to increase the risk of developing it.
About 10% of people with HCL have this variant form of the disease, representing about 60-75 new cases of HCL-V each year in the U.S. While classic HCL primarily affects men, HCL-V is more evenly divided between males and females. While the disease can appear at any age, the median age at diagnosis is over 70.Similar to B-cell prolymphocytic leukemia (B-PLL) in chronic lymphocytic leukemia, HCL-V is a more aggressive disease. Historically, it has been considered less likely to be treated successfully than is classic HCL, and remissions have tended to be shorter. The introduction of combination therapy with concurrent rituximab and cladribine therapy, though, has shown excellent results in early follow-up. As of 2016, this therapy is considered the first-line treatment of choice for many people with HCL-V.Many older treatment approaches, such as interferon-alpha, the combination chemotherapy regimen "CHOP", and common alkylating agents such as cyclophosphamide, showed very little benefit. Pentostatin and cladribine administered as monotherapy (without concurrent rituximab) provide some benefit to many people with HCL-V, but typically induce shorter remission periods and lower response rates than when they are used in classic HCL. More than half of people respond partially to splenectomy.In terms of B-cell development, the prolymphocytes are less developed than are lymphocytes or plasma cells, but are still more mature than their lymphoblastic precursors.