LYMPHOSARCOMA encyclopedia topics

Lymphoma a type of neoplasm that originates in lymphocytes (a type of white blood cell in the vertebrate immune system). They often originate in lymph nodes, presenting as an enlargement of the node (a tumor). Lymphomas are closely related to lymphoid leukemias, which also originate in lymphocytes but do not form tumors. There are many types of lymphomas, and in turn, lymphomas are a part of the broad group of diseases called hematological neoplasms.

Thomas Hodgkin published in 1832 the first description of lymphoma, specifically of the form named after him, Hodgkin's lymphoma. Since, many other forms of lymphoma have been described and many classifications proposed. The 1982 Working formulation classification became very popular. It introduced the category Non-Hodgkin lymphoma (NHL), itself divided into 16 different diseases. However, since these different lymphomas have little in common with each other, the NHL label is of limited usefulness for doctors or patients and is slowly being abandoned. The latest classification by the WHO (2001) lists 43 different forms of lymphoma divided in four broad groups.

Some forms of Lymphoma are indolent (e.g. Small lymphocytic lymphoma), compatible with a long life even without treatment, whereas other forms are aggressive (e.g. Burkitt's lymphoma), causing rapid deterioration and death. The prognosis therefore depends on the correct classification of the disease, established by a pathologist after examination of a biopsy. Chemotherapy is prescribed by an oncologist, radiation therapy by a radiation oncologist.

Although older classifications referred to histiocytic lymphomas, these are recognized in newer classifications as of B, T or NK cell lineage. True Histiocytic malignancies are rare and are classified as sarcomas.

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 lymphoma in particular accounts for less than one percent of all cases of cancer in the United States.

Because the whole system is part of the body's immune system, patients with a weakened immune system, such as from HIV infection or from certain drugs or medication, also have a higher incidence of lymphoma.

Classification

REAL classification

In the 1990s, the Revised European-American Lymphoma (REAL) Classification attempted to apply immunophenotypic and genetic features in identifying distinct clinicopathologic NHL entities.

WHO classification

The WHO Classification, published in 2001, is the latest classification of lymphoma and is based on the "Revised European-American Lymphoma classification" (REAL). This system attempts to group lymphomas by cell type, i.e., the normal cell type that most resembles the tumor. There are three large groups: the B cell, T cell, and natural killer cell tumors. Other less common groups, including Hodgkin's lymphoma, are also recognized. (ICD-O codes are provided where available.)

Mature B cell neoplasms

Chronic lymphocytic leukemia/Small lymphocytic lymphoma
B-cell prolymphocytic leukemia
Lymphoplasmacytic lymphoma (such as Waldenström macroglobulinemia)
Splenic marginal zone lymphoma
Plasma cell neoplasms:

Extranodal marginal zone B cell lymphoma, also called MALT lymphoma
Nodal marginal zone B cell lymphoma (NMZL)
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

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

Classical Hodgkin lymphomas:

Nodular sclerosis
Mixed cellularity
Lymphocyte-rich
Lymphocyte depleted or not depleted

Nodular lymphocyte-predominant Hodgkin lymphoma

Immunodeficiency-associated lymphoproliferative disorders

Associated with a primary immune disorder
Associated with the Human Immunodeficiency Virus (HIV)
Post-transplant
Associated with Methotrexate therapy

Working formulation and Non-Hodgkin lymphoma

The 1982 Working Formulation is a classification of Non-Hodgkin Lymphoma. It has since been replaced by other lymphoma classifications, the latest published by the WHO in 2001, but is still used by cancer agencies for compilation of lymphoma statistics.