Clinical utility of repeated IgH gene rearrangement testing for the diagnosis and surveillance of gastric MALT lymphoma.

Gastric MALT lymphoma diagnosis relies on histopathological findings and immunoglobulin H gene (IgHr) rearrangement testing, which reflects monoclonal immunoglobulin proliferation. This study aimed to clarify the role of IgHr in the diagnosis, treatment prediction, and surveillance of gastric MALT lymphoma. Of the 152 suspected cases, 131 were definitively diagnosed using a combination of IgHr and pathology, with pathological findings considered the gold standard. Patients with discrepancies between IgHr and pathology underwent re-evaluation. The relationship between IgHr status, clinicopathological features, and treatment outcomes was analyzed. IgHr and histopathology were assessed over 2 years in 41 patients after pathological complete remission (pCR). IgHr positivity was 69.5% at initial biopsy and 90.8% after two biopsies. IgHr-positive cases had higher H. pylori infection rates and better CR rates post-eradication. Patients with IgHr positivity at pCR had higher recurrence rates (16.7%). IgHr positivity gradually declined among 37 non-recurrent cases (CR: 56.8%, 6 M: 45.9%, 1Y: 21.6%, 2Y: 10.8%), indicating a delay between pCR and IgH-negative conversion. Repeated biopsies may improve the accuracy of gastric MALT lymphoma diagnosis. IgHr-positive status at pCR may signal higher recurrence risk, underscoring the need for careful post-CR surveillance. Surveillance should account for potential delays in IgHr-negative conversion.