Employing PCR Technique in Assessment of Monoclonality in Large B-cell Non-Hodgkin's Lymphoma

Most B-cell malignancies are diagnosed based on morphologic and immunohistochemical criteria. Some cases, however, still present a challenge for the pathologist to discriminate between reactive hyperplasia and neoplastic disorders. Molecular techniques can be used as a helpful diagnostic tool in these cases. In this study, we assessed the value of polymerase chain reaction (PCR) technique in determination of monoclonality of immunoglobulin heavy chain gene rearrangements for the diagnosis of large B-cell non-Hodgkin's lymphoma (NHL) in paraffin embedded tissue samples. DNA was extracted from paraffin embedded tissues of 44 diffuse large B-cell lymphoma (DLBCL) cases and 20 samples of reactive lymphoid tissues from appendix and tonsils as control. Framework 3 and the joining region (FR3/JH) of the variable segment of the immunoglobulin heavy chain gene were amplified using degenerated primers. PCR products from each sample were analyzed on 8% polyacrylamide gels following AgNO3 staining. Monoclonal rearrangements were identified in 33 of 44 cases (75%) of DLBCL using FR3/JH primers. Monoclonal IgH gene rearrangements were not detected in any of the reactive lymphoid hyperplasic samples. All these control cases showed polyclonal pattern. Through PCR analysis, using degenerated primers, monoclonality was demonstrated in 75% of DLBCL cases. This technique can thus be used as a sensitive, reliable and valuable diagnostic supplement to conventional morphologic examination and immunohistocytochemical evaluation of lymphoproliferative disorders, particularly in cases with restrictions in amount or type of analytic material.