| Non-Hodgkin Lymphomas | |
|---|---|
| Classification and external resources | |
Micrograph of mantle cell lymphoma, a type of non-Hodgkin lymphoma. Terminal ileum. H&E stain. |
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| ICD-10 | C82-C85 |
| ICD-9 | 200, 202 |
| ICD-O: | 9591/3 |
| OMIM | 605027 |
| DiseasesDB | 9065 |
| MedlinePlus | 000581 |
| eMedicine | med/1363 ped/1343 |
| MeSH | D008228 |
The non-Hodgkin lymphomas (NHLs) are a diverse group of blood cancers that include any kind of lymphoma except Hodgkin's lymphomas.[1] Types of NHL vary significantly in their severity, from indolent to very aggressive.
Lymphomas are types of cancer derived from lymphocytes, a type of white blood cell. Lymphomas are treated by combinations of chemotherapy, monoclonal antibodies, immunotherapy, radiation, and hematopoietic stem cell transplantation.
Non-Hodgkin lymphomas were classified according to the 1982 Working Formulation which recognizes 16 types. The Working Formulation is now considered obsolete, and the classification is commonly used primarily for statistical comparisons with previous decades. The Working Formulation has been superseded twice.
The latest lymphoma classification, the 2008 WHO classification, largely abandoned the "Hodgkin" vs. "Non-Hodgkin" grouping. Instead, it lists over 80 different forms of lymphomas in four broad groups.[2]
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Hodgkin lymphoma (H, Hodgkin disease), described by Thomas Hodgkin in 1832, was the first form of lymphoma described and defined. Other forms were later described and there was a need to classify them. Because Hodgkin lymphoma was much more radiation-sensitive than other forms, its diagnosis was important for oncologists and their patients. Thus, research originally focused on it. The first classification of Hodgkin lymphoma was proposed by Robert J. Luke in 1963.
While consensus was rapidly reached on the classification of Hodgkin lymphoma, there remained a large group of very different diseases requiring further classification. The Rappaport classification, proposed by Henry Rappaport in 1956 and 1966, became the first widely accepted classification of lymphomas other than Hodgkin. Following its publication in 1982, the Working Formulation became the standard classification for this group of diseases. It introduced the term non-Hodgkin lymphoma (NHL) and defined three grades of lymphoma.
However, NHL consists of 16 different conditions that have little in common with each other. They are grouped by their aggressiveness. Less aggressive non-Hodgkin lymphomas are compatible with a long survival while more aggressive non-Hodgkin lymphomas can be rapidly fatal without treatment. Without further narrowing, the label is of limited usefulness for patients or doctors.
The Centre for Disease Control and Prevention (CDC) included non-Hodgkin's lymphoma (NHL) as AIDS-defining cancers in 1987.[3] Immune suppression rather than HIV itself is implicated in the pathogenesis of this malignancy, with a clear correlation between the degree of immune suppression and the risk of developing NHL.[4] HIV-infected patients are at an increased risk for developing both Hodgkin lymphoma and NHL when compared with the general population.[5] The excess of high-grade NHL was first reported in 1984 following the description of NHL in 90 homosexual men with AIDS. The relative risk of NHL among HIV-infected patients is 150-250-fold higher than in the general population.[6]
Nevertheless, the Working Formulation and the NHL category continue to be used by many. To this day, lymphoma statistics are compiled as Hodgkin's vs non-Hodgkin lymphomas by major cancer agencies, including the National Cancer Institute in its SEER program, the Canadian Cancer Society and the IARC.
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