Bone marrow lymphoma. Light microscopy of a bone marrow smear. Non-Hodgkin lymphoma ( nhl ) involving the bone marrow shows an increased lymphoid population. Non-Hodgkin lymphoma is a type of cancer that affects the lymphatic system, a network of vessels and glands found throughout your body. The main symptom of non-Hodgkin lymphoma is swollen glands that do not go away. The main treatments for non-Hodgkin lymphoma are chemotherapy, radiotherapy and anti-cancer medicines called monoclonal antibodies. The exact cause of non-Hodgkin lymphoma is unknown. It's more common in people who have a weakened immune system. Magnification 150 x when printed at 10 centimetres wide.