Hairy cell leukaemia

Hairy cell leukaemia is a rare, slow-growing type of blood cancer affecting B lymphocytes, a type of white blood cell, named for the characteristic hair-like projections seen on the cancerous cells under a microscope. It typically affects older adults, more commonly men. It is one of the more treatable forms of leukaemia.

The exact cause is not well understood, though a specific genetic mutation (BRAF V600E) is found in most cases and is thought to drive the abnormal cell growth. It is not typically an inherited condition passed through families. Occupational exposure to certain chemicals has been suggested as a possible risk factor in some studies, though this link is not firmly established.

Common symptoms include fatigue, recurrent infections due to low normal white blood cell counts, easy bruising or bleeding, and abdominal fullness from an enlarged spleen. Some people are diagnosed incidentally through a routine blood test before symptoms develop. Symptoms often develop gradually given the slow-growing nature of the disease.

While it is a cancer and needs proper specialist management, hairy cell leukaemia generally has a very good long-term outlook with modern treatment, and many people achieve long remissions. The main risks relate to complications from low blood counts, such as infection or bleeding, before treatment is started. With appropriate treatment, most people live many years with a good quality of life.

Treatment typically involves a short course of chemotherapy, often with a drug called cladribine, which produces high remission rates for many patients. Some people do not need immediate treatment and are instead monitored if the disease is not causing significant problems. Additional targeted therapies are available for cases that relapse or do not respond fully to initial treatment.

Many people achieve long-term remission, sometimes lasting many years or even decades, after treatment, though the condition can sometimes relapse and need further treatment. It is often managed more like a chronic condition with excellent long-term control rather than a single definitive cure. Regular follow-up monitoring helps catch and treat any relapse early.

Both are slow-growing blood cancers affecting B lymphocytes, but hairy cell leukaemia has a distinctive cell appearance and different pattern of blood and bone marrow involvement, often with a notably enlarged spleen and low blood counts, compared with chronic lymphocytic leukaemia. Specific laboratory tests, including flow cytometry and looking for the characteristic BRAF mutation, help distinguish the two. Treatment approaches also differ between the two conditions.

Regular follow-up blood tests are needed to monitor for relapse, typically at increasing intervals over the years following successful treatment. Any new symptoms such as recurrent infections, unusual bruising, or fatigue should be reported promptly between scheduled appointments. Long-term haematology follow-up is standard given the possibility of late relapse.

See a doctor if you have unexplained fatigue, recurrent infections, easy bruising, or abdominal fullness, so blood tests can be arranged to investigate the cause. A private haematology referral for assessment can typically be arranged within about two weeks. Because the condition is rare, being seen by a haematologist experienced in blood cancers helps ensure an accurate diagnosis and appropriate treatment plan.