Large B cell diffuse lymphoma is a rare form of immune system cancer characterized by abnormal development and overproduction of B cells, a type of white blood cell. B cells are essential to the immune system because they produce antibodies that are responsible for recognizing foreign material and signalling the body to attack them. Individuals with this disorder may experience symptoms such as enlarged lymph nodes, fatigue, night sweats, and higher frequency of illness. Doctors often diagnose this form of cancer early, since symptoms are apparent. Treatment depends on the stage of the cancer. If the cancer has progressed, doctors may suggest patients undergo chemotherapy or radiotherapy to destroy cancerous B cells.