Types of lymphoma cancer can be classifihttp://www.blogger.com/img/blank.gifed into 2 main types: Hodgkin’s lymphoma and non Hodgkin’s lymphoma. While both types of cancer develop in the same way, the single factor that distinguishes the two is a single type of cell – the Reed Sternberg cell. This cancerous cell type is found only in Hodgkin’s lymphoma and can be distinguished from other types of lymphoma by the way it appears under a microscope. Hodgkin here is refers to Thomas Hodgkin who published the first description of lymphoma in 1832. Since then, many other forms of lymphoma have been described, grouped under several proposed classifications. The 1982 Working formulation classification became very popular. It introduced the category of non-Hodgkin lymphoma (NHL), divided into 16 different diseases. It excluded the Hodgkin lymphomas and divided the remaining lymphomas into four grades (Low, Intermediate, High, and Miscellaneous) related to prognosis, with some further subdivisions based on the size and shape of affected cells. This purely histological classification included no information about cell surface markers, or genetics, and it made no distinction between T-cell lymphomas or B-cell lymphomas. Because these different types of lymphomas cancer have little in common with each other, the NHL label is became obsolet.
In 1990s, the Revised European-American Lymphoma (REAL) Classification attempted to apply immunophenotypic and genetic features in identifying distinct clinicopathologic entities among all the types of lymphomas cancer except Hodgkin’s lymphoma. The latest classification by the WHO (in 2001) lists 43 different forms of lymphoma divided in four broad groups based upon the foundations laid within the REAL. This system attempts to group lymphomas by cell type and defining phenotypic, molecular or cytogenetic characteristics. There are three large groups: the B cell, T cell, and natural killer cell tumors. Hodgkin’s lymphoma is now recognized as being a tumor of lymphocytes of mature B cell lineage.
The different categories of lymphoma can seem very complicated, but they are based on:
* The appearance or histology of the cancer cells under a microscope.
* What kinds of genetic mutations they carry.
* Whether they form tight clusters (nodular) or are spread throughout a lymph node or other organ of the body (diffuse).
* What type of cell they arose from.
* What types of proteins the lymphoma cells have on their surface.
* Where they occur in the body.
It is often difficult to group lymphoma into definite categories because many lymphomas have traits overlap with another types of lymphoma.