Stages of Non-Hodgkin’s lymphoma

After the diagnosis of NHL has been made, the doctor is interested to know from his pathologist as to whether the NHL is of high grade or low grade and whether it is of T or B cell origin. The first is assessed by the pathologist by microscopic analysis of the biopsy specimen; in low grade tumours the cells often resemble normal small lymphocytes in many regards but will show some characteristics that are diagnostic of NHL and others which help the pathologist to further subtype the NHL.

 

For example the pathologist may say that the tumour is a follicular, low grade NHL, which means that he has seen the typical small round lymphocyte NHL population but also that this is enveloped within groupings/follicles; this is a common type of low grade NHL.

 

In high grade lymphomas, the pathologist often encounters large bizarre looking malignant lymphocytes, often with many in cell division (mitosis); this is a more aggressive/faster growing cancer. The distinction between T and B cells is made by a process called immunophenotyoping, and there nowadays further subdivisions within the lineages made other immunological tests. For example there are now available a battery of antibodies directed at surface immunoglobulin light chains and the presence of some of these on B cell lineage NHL can be used to subtype (e.g. CD numbering).

 

Recently, genetic analysis of NHL cells has become a recent science in itself; gene re-arrangement is found in many NHL and engenders excitement in the profession who believe that it is getting closer to the exact genetic defect in this cancer. Recently, the technique of PCR (polmerase chain reaction) technology has been used in gene re-arrangement analysis to detect clonal populations at incredibly low levels and is therefore of extreme interest in the establishment of cure (i.e. that there is no NHL left in the body at the end of a therapy programme).

 

There have been many different classifications of NHL and the current one is called the REAL classification but it will not be the last and the above principles should suffice for this discussion, at present.