Symptoms

In hairy cell leukemia, the "hairy cells" (malignant B lymphocytes) accumulate in the bone marrow, interfering with the production of normal white blood cells, red blood cells, and platelets. Consequently, patients may develop infections related to low white blood cell count, anemia and fatigue due to a lack of red blood cells, or easy bleeding due to a low platelet count. 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.

Hairy cell leukemia is an uncommon hematological malignancy characterized by an accumulation of abnormal B lymphocytes. It is usually classified as a sub-type of chronic lymphoid leukemia. Hairy cell leukemia makes up approximately 2% of all leukemias, with fewer than 2,000 new cases diagnosed annually in North America and Western Europe combined.

Hairy cell leukemia was originally described as histiocytic leukemia, malignant reticulosis, or lymphoid myelofibrosis in publications dating back to the 1920s. 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 1958. Its common name, which was coined in 1966, is derived from the "hairy" appearance of the malignant B cells under a microscope.

CLL treatment focuses on controlling the disease and its symptoms rather than on an outright cure. CLL is treated by chemotherapy, radiation therapy, biological therapy, or bone marrow transplantation. Symptoms are sometimes treated surgically (splenectomy removal of enlarged spleen) or by ("de-bulking" swollen lymph nodes).radiation therapy. Initial CLL treatments vary depending on the exact diagnosis and the progression of the disease, and even with the preference and experience of the health care practitioner. There are dozens of agents used for CLL therapy. 

Decision to treat

While generally considered incurable, CLL progresses slowly in most cases. Many people with CLL lead normal and active lives for many years—in some cases for decades. Because of its slow onset, early-stage CLL is, in general, not treated since it is believed that early CLL intervention does not improve survival time or quality of life. Instead, the condition is monitored over time to detect any change in the disease pattern.

The disease is easily diagnosed. CLL is usually first suspected by the presence of a lymphocytosis, an increase in one type of the white blood cell, on a complete blood count (CBC) test. This frequently is an incidental finding on a routine physician visit. Most often the lymphocyte count is greater than 4000 cells per microliter (µl) of blood, but can be much higher. The presence of a lymphocytosis in an elderly individual should raise strong suspicion for CLL, and a confirmatory diagnostic test, in particular flow cytometry, should be performed unless clinically unnecessary.

The diagnosis of CLL is based on the demonstration of an abnormal population of B lymphocytes in the blood, bone marrow, or tissues that display an unusual but characteristic pattern of molecules on the cell surface. This atypical molecular pattern includes the coexpression of cells surface markers cluster of differentiation 5 (CD5) and cluster of differentiation 23 (CD23). In addition, all the CLL cells within one individual are clonal, that is, genetically identical. In practice, this is inferred by the detection of only one of the mutually exclusive antibody light chains, kappa or lambda, on the entire population of the abnormal B cells. 

B-cell chronic lymphocytic leukemia (B-CLL), also known as chronic lymphoid leukemia (CLL), is the most common type of leukemia. Leukemias are cancers of the white blood cells (leukocytes). CLL affects B cell lymphocytes. B cells originate in the bone marrow, develop in the lymph nodes, and normally fight infection by producing antibodies. In CLL, the DNA of a B cell is damaged, so that it cannot produce antibodies.