I

Limited to one lymphatic tissue site (lymph node, thymus, or spleen), or only one site outside the lymphatic system (IE)*

II

Involves two or more lymph node regions on the same side of the diaphragm, above or below it (for example, some enlarged nodes in the neck and some in the armpit), or extension outside an involved lymph node area with or without other lymph node areas on the same side of the diaphragm (IIE)*

III

Involves spleen and lymph node regions above and below the diaphragm (for example, some enlarged nodes in the neck and some in the groin)

IV

Involves other parts of the body (such as the bone marrow, lungs, or liver), as well as lymph nodes