Detection of Follicular Lymphoma

1 translocation type with breakpoint in the MBR = Exon 1= Exon 2= Exon 3 MBR=J=J=//=C=TE 

MBR major breakpoint region MCR minor cluster region V variable segments D diversity segments J joining segments C constant region TE transcriptional enhancer 

The same t(14 18)(q32 q21) translocation described in the follicular lymphomas has been also identified in 15-35% of diffuse large B-cell lymphomas, a part of which seems to be transformed from the follicular lymphoma after the accumulation of other genetic abnormalities, in these cases the presence of the t(14 18) translocation indicates a poor prognosis. The overexpression of bd-2 is also found in many other lymphoid, myeloid and solid neoplasms. It is important to mention that the expression or the overexpression of bd-2 is not equivalent to the presence of the t(14 18) translocation-specific follicular lymphoma as it is expressed in many normal cells and in different tumors. The bd-2 is normally expressed in breast epithelium and many non-neoplastic lymphocytes including the small lymphocytes of mantle and marginal zones as well as thymus and many T-cell populations. Furthermore, bd-2 is frequently expressed in many soft tissue tumors such as solitary fibrous tumor, synovial sarcoma and rhabdomyosarcoma in addition to breast carcinoma and many lymphoma types as CLL and marginal cell lymphoma. 

The t(14 18) translocation in follicular and diffuse large B-cell lymphoma can be detected by PCR-based molecular methods using consensus primers to both bd-2 and JH regions. The PCR-based method allows the use of smaller amounts of DNA to detect this translocation, even low molecular DNA extracted from formalin-fixed paraffin-embedded tissue, bone marrow or fine needle aspiration. This method is efficient for the primary diagnosis of follicular lymphoma or to detect minimal residual tumor cells that are below the limit of detection using conventional diagnostic methods espedally after chemotherapy or bone marrow transplantation. 

It is also suitable to detect tumor cells in autologous bone marrow prepared for transplantation. Long-term studies show that patients how achieved complete molecular remission after chemotherapy or stem cell transplantation have an improved outcome compared with patients with PCR detectable disease. However, it is important to point out that some studies demonstrated the presence of this translocation in circulating lymphocytes of healthy individuals, but in very rare cases. 

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