Non-Hodgkin lymphoma
Non-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 most common symptom of non-Hodgkin lymphoma is a painless swelling in a lymph node, usually in the neck, armpit or groin.
Non-Hodgkin lymphoma is caused by a change (mutation) in the DNA of a type of white blood cell called lymphocytes, although the exact reason why this happens isn't known.
If you see your GP because you're concerned about symptoms of non-Hodgkin lymphoma, they'll ask about your health and carry out a simple physical examination.
Non-Hodgkin lymphoma is usually treated with cancer-killing medication or radiotherapy, although some people may not need treatment straight away.
Some people treated for non-Hodgkin lymphoma experience long-term problems, even if they've been cured.