Clonality testing of lymphoproliferative disorders in a large cohort of primary and consultant biopsies

Abstract

Background. Lymphoproliferative disease often presents the clinician and pathologist with a diagnostic dilemma, particularly in the early course of the disease. Methods. We used modified BIOMED-2 protocols to detect monoclonal expansions of immunoglobulin heavy chain (IgH) and T-cell receptor (TCR) genes in 957 formalin-fixed paraffin-embedded samples from 717 patients. To eliminate false-positive results, heteroduplex analysis was used after PCR reactions. The impact of different fixatives on DNA quality and performance of PCR was assessed. Results. In the class of B lymphomas we detected clonal IgH rearrangement in nearly 80% of cases and in the class of T lymphomas in 64% of cases. Performance of the assays was 94.7% and 92.5% for IgH and TCR clonality, respectively. Clonality rates in various B and T lymphomas were in concordance with previous studies. We also present 10 difficult cases where PCR analysis of IgH and TCR gene rearrangements significantly contributed to a decision on the correct diagnosis. Conclusion. These results confirm that the PCR-based analysis is suitable as a routine method and is helpful in establishing a diagnosis in morphologically unclear cases.