Early diagnosis of gastric lymphoma: gene rearrangement analysis of endoscopic biopsy samples.

The diagnosis of gastric lymphoma in endoscopic biopsy specimens remains difficult despite the emergence of accepted criteria for the histologic diagnosis of lymphomas originating from mucosa-associated lymphoid tissue (MALT). The sensitivity and validity of immunoglobulin (Ig) gene rearrangement analysis of mucosal biopsies for the diagnosis of malignant B-cell lymphoma were investigated in comparison with conventional histology and immunohistology. Biopsy specimens from 34 different endoscopies of 20 patients with a previous history, or tentative diagnosis of gastric lymphoma, and 12 control samples were analyzed for the presence of clonal Ig gene rearrangements. A clonal B-cell population was detected by Southern blot analysis in all patients with a definitive histologic diagnosis of lymphoma. In addition, in two patients the detection of clonal rearrangements in biopsy specimens preceded by several months the histologic diagnosis of lymphoma, and clonality was confirmed in three further patients where histology remained inconclusive. In some cases of low-grade MALT-lymphoma, discrete spreading of malignant cells within chronically inflamed mucosa was suggested by the presence of identical clonal rearrangements in all simultaneously obtained biopsies, with or without histologically detectable involvement by lymphoma. Our results show that immunoglobulin gene rearrangement studies of endoscopic biopsy samples are an additional powerful tool for the diagnosis of gastric lymphoma, especially for detecting early recurrence, and improve the preoperative assessment of the extent of mucosal involvement.