Hodgkin lymphoma is an uncommon form of cancer in the lymphatic system.

The lymphatic system is part of your immune system and is a network of vessels and glands spread throughout your body. Clear fluid called lymph, flows through the lymphatic vessels and contains infection-fighting white blood cells known as lymphocytes. These lymphocytes originate in the bone marrow and circulate through the lymphatic system and into the blood stream.

In Hodgkin lymphoma, a particular type of lymphocyte; the B-lymphocytes start to multiply in an abnormal way and begin to collect together causing lumps or tumours. These lumps are most often located in lymph nodes (glands) within the lymphatic system.

The most common symptom of Hodgkin lymphoma is a painless swelling in a lymph node, usually in the neck, armpit or groin.

Other symptoms can include; itching, repeated infections and fatigue.

Hodgkin lymphoma can develop at any age, but it mostly affects young adults in their 20s and older adults over the age of 60. Slightly more men than women are affected.

Around 1,900 people are diagnosed with Hodgkin lymphoma in the UK each year.

The exact cause of Hodgkin lymphoma is unknown. Your risk of developing the condition is slightly increased if you have a medical condition that weakens your immune system, you take immunosuppressant medication, or you have previously been exposed to a common virus called the Epstein-Barr virus, which causes glandular fever.

You also have a small increased risk of developing Hodgkin lymphoma if a first-degree relative (parent, sibling or child) has had the condition.