Hairy Cell Leukaemia

HCL is a very rare form of cancer, with approximately 170 new cases diagnosed each year in the UK. 

(Estimated by applying HMRN age and sex specific rates to 2001 UK population census).  It usually develops very slowly and as such is referred to as ‘chronic’.  HCL affects a type of white blood cell called a B‑lymphocyte, and under a microscope, these abnormal blood cells have hair like projections on their surfaces. This is where the name hairy comes from.

As with other forms of blood cancer the bone marrow of patients with HCL makes too many immature, poorly functioning white blood cells. Over time these abnormal white cells fill up the bone marrow, reducing the number of normal white blood cells, red blood cells and platelets that can be made.

In HCL, these abnormal white blood cells also build up in the spleen and cause it to grow bigger. An enlarged spleen may also remove normal blood cells from the bloodstream. This can also reduce the number of red blood cells and normal white blood cells in the blood.

Having too few red blood cells makes you tired and breathless (anaemic). And if you don’t have enough platelets, you can have bleeding problems.  Too few or poorly functioning white blood cells can lead to repeated or prolonged infections. 

Causes

We don’t know what causes hairy cell leukaemia. The only risk factors we know of are age and gender. Hairy cell leukaemia tends to be more common after the age of 30. The most common age for diagnosis is around 50 (40 – 60).  It is more common in men. About 5 times as many men are diagnosed with this type of leukaemia as women.

^*A risk factor is anything that increases your risk of getting a disease/cancer.   Different diseases/cancers have different risk factors. Having one or more risk factors for any disease does not mean that you will definitely get it. Finally although a risk factor can increase your chances of getting a cancer, it does not cause cancer.

Reviewed March 2013