What does Ann Arbor Stage III signify?

Ann Arbor Stage III is indicative of lymphoma that involves multiple lymph node regions both above and below the diaphragm, meaning that the disease has spread beyond a localized area. This stage reflects a more advanced state of the disease compared to earlier stages, suggesting a greater extent of lymphatic involvement. The classification is pivotal for determining the appropriate treatment plan and understanding the prognosis, as Stage III signifies systemic rather than localized involvement. In contrast to the other options, which either describe fewer lymph node regions or involvement of organs without lymph node participation, Stage III specifically highlights the comprehensive dissemination of lymphatic involvement across the diaphragm.