Which stage of lymphoma involves more than one lymph node but is confined to one side of the diaphragm?

In the context of lymphoma staging, the description provided matches Stage II. Stage II is characterized by the involvement of two or more lymph nodes on the same side of the diaphragm, which aligns with the criteria for this particular stage.

Understanding how lymphomas are categorized is essential. The Ann Arbor staging classification begins with Stage I, which indicates involvement of a single lymph node or a single extralymphatic site. As the stages progress, Stage II incorporates the involvement of multiple lymph nodes but remains contained to one side of the diaphragm, distinguishing it from later stages.

Stage III, in contrast, indicates that the lymphoma is present in lymph nodes on both sides of the diaphragm. Stage IV represents more advanced disease, where the lymphoma has spread beyond the lymphatic system to other organs. Thus, the specific mention of lymph nodes being more than one but still on one side of the diaphragm clearly confirms that Stage II is indeed the correct answer.