The staging system used for non-Hodgkin's lymphomas is the Ann Arbor convention developed for the staging and treatment (primarily with radiation) of Hodgkin's disease.
Stage I Involvement of a single lymph node region (Stage I) or localized involvement of a single organ or site other than lymph nodes (IE).
Stage II Involvement of two or more lymph node regions on the same side of the diaphragm (either above or below the breathing muscle separating the chest from the abdomen) (Stage II) or localized involvement of a single associated organ or site other than lymph nodes (extralymphatic) and its regional lymph nodes, with or without other lymph node regions on the same side of the diaphragm (IIE).
Stage III Involvement of lymph node regions on both sides of the diaphragm (Stage III) that may also be accompanied by localized involvement of an extralymphatic organ or site (IIIE), involvement of the spleen (IIIS) or both (IIIS+E).
