Non-Hodgkin lymphomas are the most common and there are about 61 known types of the disease. Unlike Hodgkin lymphoma, Non-Hodgkin lymphoma does not involve Reed-Sternberg cells. It is difficult to compile all types of Non-Hodgkin lymphoma due to the great amount and different methods used to do so. Therefore, the current standard classification is the one defined by the WHO, which is based on its appearance when analyzed under a microscope, the chromosome features of the lymphoma cells, the existence of certain proteins, and whether it is originated in B-cells or T-cells.
About 85% of the non-Hodgkin lymphomas diagnosed in the US are B-cell lymphomas, which means they are originated from this type of cell. Diffuse large B-cell lymphoma (DLBCL) is the most common one, followed by its subtypes; primary mediastinal B-cell lymphoma, a fast-growing but usually easy to treat lymphoma, and intravascular large B-cell lymphoma, a rarer lymphoma.
Follicular lymphoma, chronic lymphocytic leukemia/small lymphocytic lymphoma, mantle cell lymphoma, marginal zone B-cell lymphomas, nodal marginal zone B-cell lymphoma, nodal marginal zone B-cell lymphoma, splenic marginal zone B-cell lymphoma, Burkitt lymphoma, lymphoplasmacytic lymphoma (Waldenstrom macroglobulinemia), hairy cell leukemia, and primary central nervous system (CNS) lymphoma are also B-cell lymphomas. In addition, extranodal marginal zone B-cell lymphomas or mucosa-associated lymphoid tissue (MALT) lymphomas are characterized by appearing outside the lymph nodes.
Less than 15% of the non-Hodgkin lymphomas are T-cell lymphomas and there are numerous subtypes, most of them rare. Precursor T-lymphoblastic lymphoma/leukemia is one the biggest subgroups of T-Cell non-Hodgkin lymphomas and it can also be considered a leukemia, according to the extent of bone marrow affected. The other great group is the one of peripheral T-cell lymphomas, which includes most of the subtypes.
Cutaneous T-cell lymphomas (mycosis fungoides, Sezary syndrome, among others), adult T-cell leukemia/lymphoma, angioimmunoblastic T-cell lymphoma, extranodal natural killer/T-cell lymphoma, nasal type, enteropathy-associated intestinal T-cell lymphoma (EATL) – which is subdivided into type I and type II, anaplastic large cell lymphoma (ALCL), peripheral T-cell lymphoma are the subtypes of peripheral T-cell lymphoma.