C81-C96: Malignant neoplasms, stated or presumed to be primary, of lymphoid, haematopoietic and related tissue

C84: Mature T/NK-cell lymphomas

Mature T/NK-cell lymphomas are a group of rare cancers that develop from mature T cells and natural killer (NK) cells, which are types of white blood cells crucial for our immune response. They start in the lymphatic system, a part of your body's immune system, leading to the typical swelling of lymph nodes that many patients experience. However, they can also affect the skin, nasal cavity, intestinal tract, and other organs. The causes of these lymphomas are not well understood, but they are thought to arise from genetic mutations combined with viral infections in some cases, like the Epstein-Barr virus. They are not contagious. Symptoms can vary greatly but often include swollen lymph nodes, fatigue, unexplained weight loss, fevers, night sweats, and skin rashes. The progression of these conditions is unpredictable and changes from patient to patient.