Lymphomas are cancers of the white blood cells called lymphocytes, part of the body's immune system. In lymphoma, the lymphocytes morph into a cancer cell and accumulate in the lymph nodes and lymphatic system, where they crowd out normal lymphocytes. The two main types of lymphomas are Hodgkin's lymphoma and Non-Hodgkin's lymphoma. Hodgkin's and Non-Hodgkin's lymphomas affect different lymphocytes, so the treatment options and the course of the disease may differ.
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In Hodgkin's lymphoma, a specific type of cell called a Reed-Sternberg cell is present in the bloodstream and lymph nodes. Reed-Sternberg cells, named after the scientists who discovered them, are large cells with two nuclei easily visible under a microscope. Non-Hodgkin's lymphoma does not contain these cells, but can have a variety of different cancer cells that have different characteristics, depending on the specific subtype of non-Hodgkin's lymphoma.
According to the Leukemia and Lymphoma Society, in 2009, approximately 148,460 people were living with Hodgkin's lymphoma in the U.S. and approximately 452,720 people had non-Hodgkin's lymphoma. The incidence of Hodgkin lymphoma is higher in males, while non-Hodgkin's lymphoma occurs more often in females.
The exact causes of both Hodgkin's and non-Hodgkin's lymphoma are still undetermined, but some associations and risk factors may be involved, including infection with HIV, mononucleosis or human T-cell lymphocytotropic virus. An inherited susceptibility also is possible because family clustering is occasionally seen. Infections associated with non-Hodgkin's lymphoma include Epstein-Barr virus, HIV, human T-lymphotropic virus and Helicobacter pylori.
Clinical Features and Diagnosis
Aside from the presence of Reed-Sternberg cells in Hodgkin's lymphoma., other clinical signs differ between the two types. Hodgkin's lymphoma tends to be confined to only one lymph node in the body and spreads to the bloodstream from there, while in Non-Hodgkin's lymphoma, the cancer occurs in many different lymph nodes, according to the Merck Manuals. Hodgkin's lymphoma also spreads in a more organized fashion than Non-Hodgkin's lymphoma does and does not often involve other areas of the body. Thus, Hodgkin's lymphoma often is easier to treat than Non-Hodgkin's lymphoma.
Treatment of lymphoma depends not only on the type, but also on the stage of the disease when it is discovered. Radiation and chemotherapy are used to treat both types, but chemotherapy is the primary treatment option for non-Hodgkin's lymphoma, according to the Nemours Foundation. Hodgkin's lymphoma patients may also be treated with surgery or hematopoietic stem cell transplantation. Non-Hodgkin's lymphoma patients may be treated with both chemotherapy and radiation instead of just one of the two treatments. They may also receive treatment with anti-CD20 monoclonal antibodies or hematopoietic stem cell transplantation.