Non-Hodgkin's Lymphoma
Non-Hodgkin's Lymphoma is a difficult disease group to understand. It is mainly a malignancy of lymphoid cells which are usually from lymph nodes, however, non nodal sites may be the site of origination, such as the gastrointestinal tract or live. The diseae then may spread to other non-lymphoid areas. These diseases are much harder to diagnosis, and patients once found to have disease, it is already widespread. The disease increases with age.
Causes of Non-Hodgkin's Disease are currently unknown. It is known to be caused by a wide range of insults. These include Viruses, EBV in African Burkitt's lymphoma and organ transplant lymphoma, HTLV-1 which is endemic to Southern Japan and the Caribbean, Hepatitis C which can cause chronic low grade inflammation of the liver. Bacteria such as Helicobacter pylori, which causes gastric lymphoma. Toxins, such as radiation and pesticides.
The main risk factors for Non-Hodgkin's Lymphoma are impaired T-cell immunity, such as through organ transplantation or HIV infection. However, many patients do not have any risk factors at all.
A hypothesized mechanism by which a virus can cause Non-Hodgkin's lymphoma would be through EBV infected B cells and T cell suppression, which would allow to virus to replicate without being stopped. This would lead to a polyclonal B cell population and uncontrolled proliferation. With rapid growth and multiplication, a transforming even could be possible. These include a random cytogenietic change such as a translation or chromosome rearrangements, and or a viral gene induction.
This would then create a mutant clone, that would have a selection bias, as it would be able to grow much better than the other clones. This monoclonal lymphocyte would then become a neoplasm and form a mass.
Classification of the non-Hodgkin's diseases is one of the most complicating and most debated issues in pathology and hematology. The current classification places the disease within a set of 5 categories. The first is whether the clonal neoplastic cells are of B or T cell origin. Next, on where they are found, Follicular, Mantle, Marginal or Diffuse. Third, on whether it is a small, large or mixed population of cells. Forth, on rare occurences, such as MALT. Fifth, on the clinical relevance, such as whether the disease is indolent or aggressive.
Indolent disease defines diseases that are low graade, have a gradual onset, less symptoms, a slow progression over years, and has the possibility to transform to high grade disease. These indolent diseases are incurable, however, patients usually survive for years. High grade, aggressive disease, has a rapid onset, many more symptoms, and almost always have B symptoms, is rapidly progression and fatal without aggressive treatment. However, these diseases are potentially curable with a multiagent chemotherapy regimen.
Diagnosis is through biopsy, as with Hodgkin's disease.
1) Robbins and Cotran Pathologic Basis of Disease. Seventh Edition. Kumar, V., Abbas, A.K., and Fausto, N. 2005, Elsevier Inc.