The definition of non-Hodgkin's lymphoma is a type of cancer that develops in the lymphatic system of the body.
Stages of Development
Stage I: Lymphomas present in a single lymphatic site (i.e., spleen, lymph node) OR, in rare cases, in a single non-lymphatic site or organ.
Stage II: Two or more lymph nodes on the same side of the diaphragm are involved or a single region of lymph nodes affected along with a single non-lymphatic organ.
Stage III: Lymphatic regions on both sides of the diaphragm are affected. This stage can also be accompanied by lymph node involvement outside the main concentration and/or the spleen.
Stage IV: Spread out of cancers of one or more non-lymphatic organs with or without lymph node region involvement or tumors isolated to a single non-lymphatic organ but including additional diseases in other places such as the liver, bone marrow or cerebrospinal fluid.
An example of non-Hodgkin's lymphoma is cancer in the spleen.