PCR-based clonality analysis: a reliable method for the diagnosis and follow-up monitoring of conservatively treated gastric B-cell MALT lymphomas?

Aims: We evaluated polymerase chain reaction (PCR) amplification of specifi c immunoglobulin heavy chain (IgH) gene rearrangements as a means of demons trating monoclonality during follow-up of conservatively treated gastric MA LT lymphoma, and compared the reproducibility of PCR on sequential frozen a nd paraffin-embedded endoscopic biopsies, Mie established an association be tween clonality detected by PCR and the histological observations. Methods and results: Sixty-nine pairs of sequential frozen and paraffin-emb edded endoscopic biopsies from 21 conservatively treated patients were grad ed according to the Wotherspoon-Isaacson histological scoring system, which provides a measure of diagnostic confidence on a scale 0-5, PCR amplificat ion of the IgH gene was performed using FR3/JH and FR2/JH primers. 68/69 pa ired samples (98.5%) showed identical mono- or polyclonal PCR amplification patterns, Forty-seven out of 48 pairs of samples sharing similar histologi cal features produced identical amplification patterns in both fresh and pa raffin-embedded tissues, In comparison with the histological grading, monoc lonality was detected in 64.2% and 41.6% of samples scored 5 and 4, respect ively. Conversely, among 64 samples scored 0-3, a monoclonal pattern was ob served only in two samples, one of which was from a patient who relapsed 9 months later, Conclusions: PCR-based clonality analysis by demonstration of specific IgH gene rearrangement can be easily and reliably performed on both frozen and paraffin-embedded endoscopic biopsies. In conjunction with histological obs ervation, this method can be used as a complementary tool to monitor MALT l ymphoma regression during conservative treatment.