Lymphoma

Table of Contents

Lymphoma is any of a variety of cancer that begins in the lymphatic system. In technical terms, lymphoma denotes malignancies of lymphocytes or, more rarely, of histiocytes. Collectively, these cell types form the reticuloendothelial system and circulate in the vessels of the lymphatic system. Just as there are many types of lymphocytes, so there are many types of lymphoma. Lymphomas are part of the broad group of diseases called hematological neoplasms. Traditionally, Lymphoma is classified as Hodgkin's lymphoma, discovered by Thomas Hodgkin in 1832, and non-Hodgkin's lymphoma (all other types of lymphoma). Modern classifications of lymphoma have moved away from this artificial division.

Classification

Working Formulation

The Working Formulation, published in 1982, is primarily descriptive but remains the most widely used classification of non-Hodgkin lymphoma today.

Low grade

• Malignant Lymphoma, small lymphocytic (chronic lymphocytic leukemia)
• Malignant Lymphoma, follicular, predominantly small cleaved cell
• Malignant Lymphoma, follicular, mixed (small cleaved and large cell)

Intermediate grade

• Malignant Lymphoma, follicular, predominantly large cell
• Malignant Lymphoma, diffuse, small cleaved cells
• Malignant Lymphoma, diffuse, mixed (small and large cells)
• Malignant Lymphoma, diffuse large cells

High grade

• Malignant Lymphoma, large cell, immunoblastic
• Malignant Lymphoma, lymphoblastic
• Malignant Lymphoma, small non-cleaved cells (Burkitt's lymphoma)

Miscellaneous

• Composite
• Mycosis fungoides
• Histiocytic
• Extramedullary plasmacytoma
• Unclassifiable

REAL/WHO Classification

The WHO Classification is the latest classification of lymphoma, published by the World Health Organization in 2001. It was based upon the "Revised European-American Lymphoma classification" (REAL) and is sometimes referenced by that name.
This classification attempts to classify lymphomas by cell type, i.e. the normal cell type that most closely resembles the tumour. They are classified in three large groups: the B cell tumours, the T cell and natural killer cell tumours, Hodgkin lymphoma, and other minor groups: (ICD-O codes are provided where available)

Mature B Cell Neoplasms

• Chronic lymphocytic leukemia/small lymphocytic lymphoma
• B-cell prolymphocytic leukaemia
• Lymphoplasmacytic lymphoma/Waldenström macroglobulinemia
• Splenic marginal zone lymphoma
• Plasma cell neoplasms
   
• Plasma cell myeloma
• Plasmacytoma
• Monoclonal immunoglobulin deposition diseases
• Heavy chain diseases
• Extranodal marginal zone B cell lymphoma (MALT lymphoma)
• Nodal marginal zone B cell lymphoma
• Follicular lymphoma
• Mantle cell lymphoma
• Diffuse large B cell lymphoma
• Mediastinal (thymic) large B cell lymphoma
• Intravascular large B cell lymphoma
• Primary effusion lymphoma
• Burkitt lymphoma/leukemia lymphomatoid granulomatosis
• Mature T cell and Natural Killer (NK) Cell Neoplasms
• T cell prolymphocytic leukemia
• T cell large granular lymphocytic leukemia
• Aggressive NK cell leukemia
• Adult T cell leukemia/lymphoma
• Extranodal NK/T cell lymphoma, nasal type Enteropathy-type T cell lymphoma
• Hepatosplenic T cell lymphoma
• Blastic NK cell lymphoma
• Mycosis fungoides/Sezary syndrome
• Primary cutaneous CD30-positive
• T cell lymphoproliferative disorders
• Primary cutaneous anaplastic large cell lymphoma
• Lymphomatoid papulosis
• Angioimmunoblastic T cell lymphoma
• Peripheral T cell lymphoma, unspecified
• Anaplastic large cell lymphoma Hodgkin
• Lymphoma Nodular lymphocyte-predominant
• Hodgkin lymphoma
• Classical Hodgkin lymphoma
• Nodular sclerosis Mixed cellularity
• Lymphocyte-rich Lymphocyte depleted Immnuodeficiency-Associated
• Lymphoproliferative Disorders Associated with a primary immune disorder
• Associated with the Human Immunodeficiency Virus (HIV)
• Post-transplant Associated with Methotrexate therapy
• Histiocytic and Dendritic Cell Neoplasms
• Histiocytic sarcoma
• Langerhans cell histiocytosis
• Langerhans cell sarcoma Interdigitating dendritic cell sarcoma/tumour
• Follicular dendritic cell sarcoma/tumour
• Dendritic cell sarcoma, unspecified

Prevalence

According to the U.S. National Institutes of Health, lymphomas account for about five percent of all cases of cancer in the United States, and Hodgkin's disease in particular accounts for less than one percent of all cases of cancer in the United States.
Because the lymphatic system is part of the body's immune system, patients with weakened immune system, such as from HIV infection or from certain drugs or medication, also have a higher incidence of lymphoma.

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