Hodgkin lymphoma is an uncommon cancer that develops in the lymphatic system, which is a network of vessels and glands spread throughout your body.

The lymphatic system is part of your immune system. Clear fluid called lymph flows through the lymphatic vessels and contains infection-fighting white blood cells, known as lymphocytes.

In Hodgkin lymphoma, B-lymphocytes (a particular type of lymphocyte) start to multiply in an abnormal way and begin to collect in certain parts of the lymphatic system, such as the lymph nodes (glands). The affected lymphocytes lose their infection-fighting properties, making you more vulnerable to infection.

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

Read more about the symptoms of Hodgkin lymphoma.

Hodgkin lymphoma can develop at any age, but it mostly affects people between 20 and 40 years of age and those over 75. Slightly more men than women are affected.

Around 2,100 people are diagnosed with Hodgkin lymphoma in the UK each year.

The exact cause of Hodgkin lymphoma is unknown. However, your risk of developing the condition is increased if:

• you have a medical condition that weakens your immune system
• you take immunosuppressant medicine
• you've previously been exposed to a common virus called the Epstein-Barr virus, which causes glandular fever

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

Read more about the causes of Hodgkin lymphoma.

The only way to confirm a diagnosis of Hodgkin lymphoma is by carrying out a biopsy.

This is a minor surgical procedure where a sample of affected lymph node tissue is removed and studied in a laboratory.

Read more about diagnosing Hodgkin lymphoma.

Hodgkin lymphoma is a relatively aggressive cancer and can quickly spread through the body. Despite this, it's also one of the most easily treated types of cancer.

Your recommended treatment plan will depend on your general health and age, because many of the treatments can put a tremendous strain on the body. How far the cancer has spread is also an important factor in determining the best treatment.

The main treatments used are chemotherapy, followed by radiotherapy or chemotherapy alone. Surgery isn't generally used as a treatment for the condition.

Overall, around 8 out of 10 people with Hodgkin lymphoma live at least 5 years and most of these will be cured. However, there's a risk of long-term problems after treatment, including infertility and an increased risk of developing another type of cancer in the future.

Read more about:

• treatment for Hodgkin lymphoma
• complications of Hodgkin lymphoma