Hairy cell leukemia is a rare type of chronic lymphoid leukemia, which results in formation of excessive B lymphocytes by bone marrow cells. These cells replace healthy white blood cells, red blood cells and platelets. As a result of less white cell production, the body’s immune system weakens resulting in frequent infections and body’s inability to fight them.
It is more common in men as compared to women and mostly affects middle aged or older people. It is a chronic disease and has a very slow progression rate. It gets its name due its appearance under the microscope- with its cells having short thin protuberances that resemble hair.
What Are Hairy Cell Leukemia’s Symptoms?
Common signs and symptoms of hairy cell leukemia include splenomegaly (60-70%), hepatomegaly (40-50%), enlarged lymph nodes of abdomen (10%), weight loss, anemia (70%), thrombocytopenia (80%), lymphadenopathy (90%), hairy cells in blood (95%), adult respiratory distress syndrome, decreased immunity, decreased function of B- cells, increase in the number of abnormal white cells, bleeding disorders and hyperkalemia.
The exact cause of hairy cell leukemia is not known but mutation in the gene BRAF is considered to be one of the causes according to a research. The other causes known are exposure to toxic chemicals, radiation and wood dust.
The most common sign is splenomegaly (enlarged spleen) and the main goal of therapy is to prevent occurrence of infection and complications. Mostly patients present with massive splenomegaly and cytopenias (low blood count) in the mean age group of 50 years.
The low blood count that is caused by hairy cell leukemia mostly leads to infections and fatigue (caused by anemia). In some cases, symptoms include feeling of fullness in left upper part of the abdomen, weakness, tendency to bruise or bleed easily (due to decreased platelet count) and sudden weight loss with repeated infections, which may or may not be associated with chills and rigors. Anemia is caused due to low red blood cell count leading to decreased oxygen supply to the body that results in fatigue or weakness. In order to treat anemia the patient should take plenty of rest and well balanced diet. Sudden weight loss due to abdominal discomfort (splenic enlargement) is present and it is associated with frequent infections with chills and rigors. There could be pain below the ribs and painless lumps can be found in stomach, groin, and neck and in underarm region.
Lymphadenopathy is found in 10% of patients with hairy cell leukemia with low grade fever, which can be due to an infection caused by neutropenia. Treatment is often required for recurrent infections in patients with low blood cell count along with enlarged spleen and lymph nodes. Night sweats and abdominal discomfort are common with tendency to bleed and bruise easily.
Hepatomegaly is found in 20% of patients and approximately 30% of patients with hairy cell leukemia develop secondary cancers following treatment. It may be associated with liver dysfunction and enlargement of spleen with liver, known as hepatosplenomegaly. This causes malaise due to excessive growth of granulocytes in bone marrow, which is unrestrained in nature.
Skin changes may be seen in the form of purpura (hemorrhages under the skin) and ecchymosis due to severe thrombocytopenia (platelet count becomes less than 80,000/mm3) seen in 20% of the cases.
Management of Hairy Cell Leukemia
The goal of therapy is to reduce the risk of infections and their complications. The presence of characteristic malignant white blood cells known as hairy cells is diagnostic of hairy cell leukemia. It is therefore important to rule out other types of leukemia, which have the same presentation, but require different treatment.
If patient has cytopenia along with anemia, infections, bleeding tendencies and significantly enlarged spleen, treatment should be started immediately. Nucleosides (pentostatin and clabridine) and interferon A are drugs of choice for treatment, but nucleosides have a better remission rate, so they are used more often.
Follow up with repeat bone marrow biopsy is necessary to detect relapse early and start retreatment with either the same drugs or different ones.