Stage I: disease is located in a single region, usually one lymph node and the surrounding area. Stage II: disease is located in two separate regions, an affected lymph node or organ and a second affected area. Both affected areas are confined to one side of the diaphragm. Stage III: disease involves both sides of the diaphragm, including one organ or area near the lymph nodes or the spleen. Stage IV: diffuse or disseminated involvement of one or more extranodal organs, with or without associated lymph node involvement.