B cell lymphoma belongs to a group of cancers known as non-Hodgkin's lymphoma---cancers that originate in a specific type of white blood cells known as lymphocytes. Non-Hodgkin's lymphoma originates in both types of lymphoctyes: B cells which produce antibodies and T cells which recognize foreign invaders and produce cytokines. B cell lymphomas account for approximately 85 percent of all non-Hodgkin's lymphomas, according to the National Marrow Donor Program. Although there are several different types of B cell lymphomas, all non-Hodgkin's lymphomas are divided into stages based on the Ann Arbor Staging system as described by the American Cancer Society.
Stage I
B cell lymphomas most commonly originate in the lymph nodes---small gland-like structures that function as part of the immune system. The neck, armpits and groin areas contain lymph nodes. B cell lymphomas can, however, affect other parts of the body such as the spleen, gastrointestinal tract, testes, thyroid, skin, breast, bone or brain. In the staging system, these organs are noted with the letter "E" for extranodal organs.
Stage I, noted as an early-stage disease, describes B cell lymphoma found in one or more lymph nodes in only one region of the body. For example lymphoma found only in the lymph nodes nodes in the neck is classified as stage I B cell lymphoma. Stage I B cell lymphoma also describes lymphoma found in only one extranodal organ, noted as Stage IE.
Stage II
B cell lymphoma occurring in two or more groups of lymph nodes, with both found on the same side of the diaphragm---the muscle that separates the chest and the abdomen---is classified as stage II disease, also considered an early-stage disease. For example, stage II disease can occur in the lymph nodes of the neck and armpit, but not in the lymph nodes of the neck and groin. Stage IIE describes B cell lymphoma in a single group of lymph nodes also affecting a nearby extranodal organ.
Stage III
When lymph nodes on both sides of the diaphragm, such as the armpit and the groin, contain B cell lymphoma, the disease is classified as stage III. Stage IIIE describes cancer that affects at least two groups of lymph nodes along with at least one extranodal organ.
The spleen, an organ found in the upper left part of the abdomen, produces lymphocytes, filters and destroys old blood cells and stores blood and platelets. The spleen functions as part of the immune system, trapping foreign bodies helping to prevent infections. Stages with an "S," such as stage IIIES, describe cancer that has spread to the spleen.
Stage IV
Most B cell lymphomas are found and diagnosed during late-stage disease, which includes both stage III and stage IV. Stage IV disease describes B cell lymphoma affecting an organ not located near the affected lymph nodes. Stage IV disease also denotes any instance of B cell lymphoma spreading to the bone marrow, liver, brain, spinal cord or the lining of the lungs called pleura.
