Lymphoma is a cancer of the lymphatic system, which is part of the body's germ-fighting network. The lymphatic system includes the lymph nodes (lymph glands), spleen, thymus gland and bone marrow. Lymphoma can affect all those areas as well as other organs throughout the body, when a disease-fighting white blood cell called a lymphocyte develops a genetic mutation. The mutation tells the cell to multiply rapidly, causing many diseased lymphocytes that continue multiplying.
Painless swelling of lymph nodes in your neck, armpits or groin