Re: What distinguishes between the different types of non hodgkins lymphoma?

Dear Michelle,

The lymphomas are malignancies that arise from lymphocytes in various 
stages of differentiation or development.  In general, the classification 
of lymphomas are based on the developmental stage of lymphocyte that gives 
rise (or is believed to give rise) to the malignant clone of cells.  The 
classification of lymphomas has been somewhat controversial over the 
years, but the classification systems have themselves evolved recently as 
more has been learned about the molecular biology of lymphomas.

The earlier classifications, such as the Rapaport (1966) and Kiel (1978) 
systems, relied largely on morphologic features (appearance under the 
microscope) and immunologic features (surface markers) of the malignant 
lymphocytes.  The Working Formulation, published in 1981, was a simplified 
system that relied on morphologic criteria only and was found to be 
reproducible and a fairly good predictor of prognosis.  The Revised 
European-American Lymphoma (REAL) classification, published in 1994, is 
the most up-to-date and comprehensive system, taking into account 
morphologic, immunologic and cytogenetic (chromosomal abnormalities) 
features.  An update of the REAL classification by the World Health 
Organization (WHO) is currently under development.

In addition to exhibiting different laboratory features as described 
above, different types of lymphoma have different clinical features which 
are often very predictable based on the classification of the lymphoma.  
Some types of lymphoma (often referred to as indolent or low-grade 
lymphomas) are characterized by a very slowly progressive course over many 
years, with patients often feeling well and not requiring any treatment 
for some time before symptoms develop.  While these lymphomas often 
respond well to drug treatment (chemotherapy) and radiation therapy, they 
nearly always relapse eventually and thus are usually not curable.  In 
contrast, aggressive or intermediate- or high-grade lymphomas typically 
grow more rapidly and produce symptoms in most patients (rather than being 
present without symptoms).  While these lymphomas behave more 
aggressively, cure may be possible with aggressive chemotherapy and/or 
radiation therapy.  Other special categories of lymphoma have distinctive 
features (such as mycosis fungoides which typically affects the skin).

Recent developments in the treatment of lymphomas have included the use of 
monoclonal antibodies such as rituximab, which targets the CD20 surface 
marker on lymphoma cells.  These agents have improved the success rate of 
present treatments while adding very little in the way of adverse effects.

Good luck!

- Steve Lattanzi, M.D. (s.lattanzi@att.net)

References

DeVita VT, Hellman S, Rosenberg SA.  Cancer:  principles and practice of 
oncology.  Ed. 6.  Philadelphia, PA:  Lippincott, Williams & Wilkins, 
2001.  2215-35.

Banks PM.  Histopathology of malignant lymphomas.  In:  Williams WJ, 
Beutler E, Erslev AJ, Lichtman MA.  Hematology.  Ed. 4.  New York, NY:  
McGraw-Hill, 1990.  1031-8.