Stage 4 Hodgkin’s lymphoma is when the cancer spreads beyond the lymph nodes to distant organs, explains Mayo Clinic. In stage 4 non-Hodgkin's lymphoma, the cancer spreads outside the lymph system to organs not directly next to an affected node, according to the American Cancer Society.
Lymphoma is the seventh most common cancer in adults, and the third most common cancer in children, according to eMedicineHealth. It represents 35 different subtypes of cancer of the lymphocytes.
Lymphocytes are immune cells that circulate inside of the lymphatic system and attack foreign organisms and abnormal cells. They are comprised of T cells and B cells, and each type attacks organisms differently. While B cells produce antibodies that attach to a target, marking it for other immune cells to kill, T cells kill pathogens directly, states eMedicineHealth.
Lymphoma occurs when normal lymphocytes mutate to abnormal cells. As these cancer cells multiply, they can aggregate inside of lymph nodes and form tumors. When the tumors increase in size, they starve nearby organs of blood supply and oxygen. The abnormal cells can also travel and spread to other sites in the lymphatic system, affecting organs all over the body, explains eMedicineHealth.
Non-Hodgkin's lymphoma can originate from either abnormal B or T cells; Hodgkin's lymphoma develops exclusively from a specific line of B cells. It is important to differentiate them because clinical symptoms and physical exam results are similar in both, notes eMedicineHealth.