Large B cell lymphoma. Light micrograph (LM) of a section from a lymph node biopsy of a patient with diffuse large B cell lymphoma (DLBCL) showing abnormal, large cells spread diffusely. Diffuse large B cell lymphoma (DLBCL) is a type of non-Hodgkin lymphoma(NHL). NHL is a cancer of the lymphatic system. It develops when the body makes abnormal B lymphocytes. These lymphocytes are a type of white blood cell that normally help to fight infections. DLBCL is usually treated with a number of different chemotherapy drugs, a steroid and a targeted immunotherapy drug called rituximab (Mabthera). Magnification: x 250 when printed at 10 centimetres high.