The use of the polymerase chain reaction in the diagnosis of B-cell lymphomas from formalin-fixed paraffin-embedded tissue

In this study the use of the polymerase chain reaction (PCR) to detect monoclonality in B-cell lymphoid proliferations in archival formalin-fixed paraffin-embedded tissue was assessed. Using consensus primers against the framework 3 (FR 3) region of the immunoglobulin heavy chain gene (IgH), PCR analysis was performed on 29 low grade B-cell non-Hodgkin's lymphomas. Cases of benign lymphoid hyperplasia served as polyclonal controls. Sequenced cases of acute lymphoblastic leukaemia served as positive controls. In the lymphomas, monoclonality could be demonstrated in 18 of 29 (62%) cases. Only five of 11 (45%) follicle centre cell lymphomas were positive by this method whilst the success rate for the remainder was 13 of 18 (72%). None of the polyclonal controls gave false positive results although occasional non-specific dominant bands were present which disappeared on repeating the experiments. These results show that this method will identify monoclonality in 62% of low grade B-cell non-Hodgkin's lymphomas in archival material. The success rate is increased to 72% if follicle centre cell lymphomas are excluded. Thus, this method is a useful adjunctive test to aid diagnosis in lymphoid infiltrates when standard morphology and immunohistochemistry are equivocal.