Lymphoma is a general term meaning the transformation of cells from the immune system into cancer cells. There are two main types of lymphoma: Hodgkin's and non-Hodgkin's lymphoma. Merck Manuals, an online medical library, reports that there are 8,000 new cases of lymphoma a year nationally. Non-Hodgkin's lymphoma is more common, with 63,000 new cases a year in the U.S. The American Cancer Society notes that these two types of lymphoma differ in how they spread throughout the body, and how they respond to treatment.
Hodgkin's Lymphoma
According to Merck Manuals, Hodgkin's lymphoma occurs when a cell of the immune system, a lymphocyte, transforms into a specialized type of cancer cell called a Reed-Sternberg cell. Genes are packaged into one nucleus per cell in normal cells, but Reed-Sternberg cells have two nuclei. One common symptom of Hodgkin's lymphoma is swelling of the lymph nodes (lymphadenopathy), though this swelling is most often painless. Other symptoms include unintended weight loss, night sweats and fever. The spleen and liver may also grow larger. The tumor formed by the cancer cells may grow and inhibit other bodily functions, such as breathing, liver function (causing jaundice), difficulty breathing, or paralysis of the lower limbs.
Non-Hodgkin's Lymphoma: B cells
One type of immune cell is a B cell, which produces proteins called antibodies that attack invading germs. When the B cell becomes cancerous, the disease is called a B cell lymphoma. According to the American Cancer Society, approximately 85 percent of non-Hodgkin's lymphomas in the U.S. are B cell lymphomas. Just as there are multiple subtypes of B cells, there are also multiple subtypes of B cell lymphomas. Examples of B cell lymphoma are diffuse large B cell lymphoma, which is named for how large the cells look under the microscope; follicular lymphoma, which begin in the lymph node and are often slow growing; and mantle cell lymphoma, which most often affects men and is usually already widespread throughout the body when diagnosed.
Non-Hodgkin's Lymphoma: T cells
Another type of immune cell is a T cell, which participates in cell-mediated immunity, meaning it directly attacks invading germs. When it's a T cell that becomes cancerous in non-Hodgkin's lymphoma, it's called a T cell lymphoma. The American Cancer Society reports that this type of lymphoma makes up fewer than 15 percent of non-Hodgkin's lymphomas in the United States. There are multiple subtypes of T cell lymphoma. Precursor T lymphoblastic lymphoma occurs when the cell that ultimately turns into a T cell becomes cancerous (called a T cell precursor). This type of cancer usually begins in the thymus, where T cells develop. There are also multiple subtypes that involve mature T cells, called peripheral T cell lymphomas; these lymphomas are rare, accounting for approximately 5 percent of all lymphomas. Examples of peripheral T cell lymphomas are cutaneous T cell lymphoma, which starts in the skin; angioimmunoblastic T cell lymphoma, which usually begins in the lymph node and affects the liver and spleen; and enteropathy type T cell lymphoma, which affects people sensitive to the gluten in wheat, and begins in the intestines.
