Diffuse Large B-Cell Lymphoma, Including Mediastinal Large B-Cell Lymphoma
Diffuse large B-cell lymphoma is the most common non-Hodgkin’s lymphoma. The majority of cases include enlarged lymph nodes that can be accompanied by symptoms such as fatigue, fevers, sweats, or weight loss. Approximately one-third of the patients with this disease will have the lymphoma appear in an organ other than lymph nodes.
Essentially any organ in the body can be involved. The gastrointestinal tract is a common site for diffuse large B-cell lymphoma to be found, but lung, kidney, brain, testicle, liver, skin, bones, thyroid, etc. can be the initial site of the disease.
Three specific situations deserve special mention: (1) Diffuse (nonfollicular) large B-cell lymphoma is the most common cancer in the testicles of men over 60. (2) It can also be a brain tumor. This is particularly likely in patients with severe immunosuppression (less ability to fight disease), such as those infected by human immunodeficiency virus (HIV); it is also found in patients with no preceding illness.
Finally, (3) diffuse large B-cell lymphoma that is in the mediastinum in young women is a characteristic disease that has been known for some time. This is often referred to as mediastinal large B-cell lymphoma. It is now known that the genes expressed in these tumors are different from other diffuse large B-cell lymphomas. However, all diffuse large B-cell lymphomas are likely to respond to chemotherapy and many patients will be cured.
Follicular Lymphoma
The second most common non-Hodgkin’s lymphoma in the United States is follicular lymphoma. Symptoms for this disease almost always include enlarged lymph nodes and the disease frequently involves bone marrow. Unlike diffuse large B-cell lymphoma, which is a rapidly growing lymphoma, this tumor tends to progress much more slowly, and patients are less likely to have symptoms such as fevers, sweats, or weight loss. Occasionally, this lymphoma can begin in a site other than lymph nodes.
Over time many patients with follicular lymphoma will have the disease transform to diffuse large B-cell lymphoma. This is a serious complication. Under the microscope, patients with follicular lymphoma have varying numbers of large or transformed lymphocytes in the tumor. Patients with a higher number of large cells in the tumor are more likely to have an aggressive course. The number of large cells in the tumor is estimated by a process called grading. Patients are assigned grade I, grade II, or grade III based on the number of large cells. Patients with grade III are often treated in the same way as those with diffuse large B-cell lymphoma.
Mantle Cell Lymphoma
Mantle cell lymphoma was discovered in the 1990s. Clever pathologists could see some lymphomas that did not fit in the existing categories. The discovery of a specific chromosomal abnormality helped lead to the recognition of this disease.
Mantle cell lymphoma characteristically is found in men between 65 and 70. However, both men and women and younger patients can be affected. The symptoms usually include enlarged lymph nodes. However, the majority of patients will have involvement of bone marrow and the large bowel when a biopsy (tissue sample) is taken. This disease is somewhat more aggressive than follicular lymphoma and until recently did not respond well to available treatments.
MALT stands for mucosa associated lymphoid tissue. However, the name is somewhat misleading in that not all MALT lymphomas involve mucosa (mucous membrane). They can be found in many sites in the body.
Although the most common site for a MALT lymphoma is the stomach, it can also be found in the tissue around the eye, skin, thyroid, breast, lung, other parts of the gastrointestinal tract, etc. These are among the slowest growing lymphomas. They are frequently localized (confined to one area) and generally have a good prognosis.
Small Lymphocytic Lymphoma/Chronic Lymphocytic Leukemia
Chronic lymphocytic leukemia is a disease involving blood and bone marrow. When patients have lymphadenopathy (abnormally large lymph nodes) or other organ infiltration, the disease is often called small lymphocytic lymphoma. However, it is the same disease. This is usually a slow growing lymphoma, but it is rarely localized. It can occasionally transform to diffuse large B-cell lymphoma (a phenomenon referred to as Richter’s syndrome).
Other Marginal Zone Lymphomas
Two types of lymphoma that are related to MALT lymphomas are nodal marginal zone lymphoma and splenic marginal zone lymphoma. Nodal marginal zone lymphoma progresses much like follicular lymphoma and is a disease that is difficult for pathologists to accurately diagnose.
Splenic marginal zone lymphoma is a relatively rare lymphoma, with symptoms including an enlarged spleen and abnormal lymphocytes in the blood and bone marrow, but rarely with lymphadenopathy. Both of these diseases tend to be relatively slow growing.
Burkitt's Lymphoma
Burkitt's lymphoma is one of the fastest growing cancers. It occurs relatively more frequently in children, but can still be seen in adults. This disease constitutes a medical emergency because it grows so rapidly. Waiting several days to start treatment can have a very bad effect on the chances for cure. Burkitt's lymphoma can involve lymph nodes, bone marrow, or many body organs, including the gastrointestinal tract.