What to Know About Hairy Cell Leukemia
Medically reviewed by Douglas A. Nelson, MD
Hairy cell leukemia is a rare, slowly growing blood cancer that affects about 950 Americans each year.
The cancer is in the B cells (lymphocytes), a type of white blood cell that fights infection. Affected cells look “hairy” due to protrusions of cytoplasm that give the cells a ruffled outside border. The abnormal cells typically invade the bone marrow and spleen, causing low counts of circulating blood cells and spleen enlargement, or splenomegaly.
This article covers what the symptoms of hairy cell leukemia are and what causes the condition. It also covers how it's diagnosed and treated and how it affects life expectancy.
Nephron / Wikimedia Commons / CC BY 3.0
Characteristics of Hairy Cell Leukemia
A combination of symptoms is common in people who are diagnosed with hairy cell leukemia. Most people have symptoms arising from an enlarged spleen (such as fullness or discomfort in the abdomen) or symptoms arising from reduced blood counts (abnormal bleeding/bruising/clotting, or infection). Fever, night sweats, fatigue, and weight loss, the so-called "constitutional symptoms," are also possible.
Symptoms at diagnosis may include any of the following:
Pain or fullness in the left side of the abdomen, beneath the ribs
Feeling full without eating or after eating only a small amount
Weakness
Fatigue
Infections that range in severity
Bruising or discoloration from bleeding beneath the skin
Many people with hairy cell leukemia have fullness or discomfort in the abdomen due to an enlarged spleen, or splenomegaly. The spleen may become massive, and sometimes it can even rupture, which is a medical emergency.
Many patients also have either bruising and bleeding because of low platelet counts, or recurrent infections due to low white blood cell counts. Having low blood counts can also cause weakness and fatigue.
Takeaway
It is possible to have hairy cell leukemia with few to no symptoms.
Finally, some people have essentially no symptoms but are diagnosed with hairy cell leukemia anyway. This may occur when a clinician notices an enlarged spleen, or when labs show low blood counts during a workup for something else.
Hairy Cell Leukemia Causes
The causes of hairy cell leukemia are not fully understood. Like all cancers, genetic mutations are thought to be important in the development of this malignancy. Exposures to ionizing radiation, pesticides, and farming might be triggers, but cigarette smoke, alcohol, and obesity do not appear to be risk factors.
Hairy Cell Leukemia Diagnosis
Hairy cell leukemia is usually diagnosed by bone marrow biopsy and sampling of the liquid portion of the bone marrow, or a bone marrow aspirate.
The sampled bone marrow tissue is analyzed to determine:
Microscopic appearance of cells
Counts for each cell type
Presence or absence of protein markers (CD markers) on the cell surface
Differential Diagnosis
Some of the diseases that might look similar to hairy cell leukemia include:
Variant form of hairy cell leukemia
Splenic marginal zone lymphoma
Splenic diffuse red pulp small B cell lymphoma
Other splenic lymphomas
Prolymphocytic leukemia
The variant form of hairy cell leukemia is a rare chronic B cell malignancy that was previously thought to be a subtype of hairy cell leukemia but is now considered to be its own disease, distinct from hairy cell leukemia. The variant has less involvement of the bone marrow and is often associated with extreme elevation of the white blood cell count, often without the low blood counts seen in hairy cell leukemia.
Hairy Cell Leukemia Treatment
Some people have hairy cell leukemia with no symptoms whatsoever. If you are in this category, you might be able to go with a watch-and-wait plan for months or even years after the diagnosis before you need treatment. Treating the disease earlier when you have no symptoms or other indications for treatment has not been shown to offer any advantages.
However, treatment is usually required, and professional organizations and consensus groups have identified a number of problems or symptoms that indicate the need to treat, including the following:
Fever, night sweats, excessive fatigue, unexplained weight loss
Recurrent infection
Low red blood cell count
Low platelet count
Progressively increased white blood cell count or swelling of the lymph nodes
If you have an infection, it needs to be treated before your hairy cell leukemia is treated. That's because treatment for hairy cell leukemia suppresses the immune system.
Purine Analogs: Cladribine or Pentostatin
The treatment of hairy cell leukemia usually begins with a class of medications known as purine analogs, such as cladribine or pentostatin. If you receive a complete response, the recommendation is that you be observed until there is an indication for additional treatment.
A complete response is defined as normalization of blood counts without transfusion, absence of hairy cell leukemia cells by bone marrow biopsy and peripheral blood sample, reduced spleen size by physical examination, and absence of disease symptoms.
Other Options
If you have not had a complete response initially to pentostatin or cladribine, contemporary guidelines suggest that you might consider a clinical trial in which purine analog with or without rituximab, interferon alpha, rituximab alone or vemurafenib are being investigated.
Treatments for relapsed disease depend upon what type of remission you had with your initial therapy. If you relapse after more than two years after achieving a complete response to initial therapy with purine analog, contemporary guidelines indicate that you may benefit from retreatment with the same purine analog or treatment with an alternative purine analog with or without rituximab. Rituximab alone is considered an option for patients unable to receive purine analog.
If available, a clinical trial may be considered for patients with disease relapse within two years after achieving a complete response to initial therapy and for those with progressive disease following second-line therapy.
Treatment with an alternate purine analog with or without rituximab, interferon alpha, rituximab alone (if unable to receive purine analog) or vemurafenib are also included as options for patients with disease relapse within two years after achieving a complete response to initial therapy.
Guidelines suggest ibrutinib, vemurafenib (with or without rituximab) or moxetumomab pasudotox are appropriate options if your disease progresses after second-line therapy.
Hairy Cell Leukemia Life Expectancy
Hairy cell leukemia is quite treatable today, and many people with this cancer can expect to have long remissions and live full lives. Modern therapy does not produce a cure, but it does alleviate symptoms and allows people to achieve a near-normal lifespan.
Most people can have long-lasting remissions. When relapse occurs, it may be treated with initial therapy in some instances and newer agents in others.
Summary
Hairy cell leukemia is a rare, slow-growing blood cancer found in the lymphocytes. The cancer cells can invade the bone marrow and spleen. Symptoms include pain or fullness in the left side of the abdomen below the ribs and feeling full after eating a small amount.
Hairy cell leukemia is diagnosed with a bone marrow biopsy and a sampling of the liquid portion of the bone marrow. Treatment includes purine analogs, rituximab, and other medications.
Hairy cell leukemia is treatable, and most people can expect a normal life expectancy with treatment.
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