Lymphomas are cancers of the lymphoid cells in the body. Cancer of the lymphoid tissue can be treated using anticancer drugs, radiation or bone marrow transplantation therapy. The likelihood of the cancer being curable depends on its type, its stage and its grade.

Pathology and types

Lymphoma is a form of blood cancer but, unlike leukemia, originates in the lymph nodes rather than the bone marrow.

Lymphoma forms around 5% of all cancers in the United States and nearly half of all the blood cancers. Lymphoma is the fifth most common cancer in the United Kingdom and the most common cancer to occur under the age of 30.

There are many types of lymphoma but they are broadly categorized as Hodgkin's lymphoma and non-Hodgkin's lymphoma.

Thomas Hodgkin first described lymphoma in 1832. In 1982, the Working formulation was introduced which listed 16 lymphomas that were not Hodgkin's lymphoma. However, due to the dissimilarity between these non-Hodgkin's lymphomas (NHL), this NHL category is of little help to physicians and is gradually being abandoned.

In 2008, the World Health Organization (WHO) introduced the latest classification system for these lymphomas which now lists 70 different forms which are broadly categorized into four groups. This classification system is based on the Revised European-American Lymphoma (REAL) classification system which divides the lymphomas according to cell type and cell characteristics.

The four classes outlined by WHO include:

1. Mature B cell neoplasia including diseases such as chronic lymphocytic leukemia, plasma cell cancers and urkitt lymphomas.
2. Mature T cell and natural killer (NK) cell neoplasia such as adult T cell leukemia/lymphoma, T cell prolymphocytic leukemia and primary cutaneous CD30-positive T cell lymphoproliferative disorders.
3. Hodgkin lymphomas
4. Immunodeficiency-associated lymphoproliferative disorders such as those associated with HIV AIDS, chemotherapy or radiotherapy.