THE SIGNIFICANCE OF B-CELL CLONALITY IN GASTRIC LYMPHOID INFILTRATES

The significance of the demonstration of a clonal B-cell population in gastric lymphoid infiltrates was investigated by analysis of immunogl obulin heavy chain (IgH) gene rearrangements using sensitive polymeras e chain reactions, employing fluorescently labelled primers to target the FR3 and FR1 regions, Tissue blocks were studied showing different histological features (high-grade lymphoma, low-grade lymphoma, and ch ronic gastritis) from 12 gastrectomies for primary gastric lymphoma, t ogether with blocks showing chronic gastritis from 13 cases of gastric adenocarcinoma and biopsies from 33 patients with active Helicobacter associated chronic gastritis. Clonal IgH gene rearrangements were det ected in lymphoma samples from eight of the gastrectomies for lymphoma (67 per cent). In four of these eight specimens, clonal rearrangement s mere also detectable in the samples showing only chronic gastritis. Three of 28 (11 per cent) informative biopsies showing active Helicoba cter associated chronic gastritis had detectable clonal populations. C lonal rearrangements mere also demonstrated in two of eight (25 per ce nt) informative blocks showing chronic gastritis from eight gastrectom ies for adenocarcinoma. It is concluded that the detection of a clonal population in a suspicious lymphoid infiltrate does not confirm the d iagnosis of lymphoma, nor does the absence of such a population imply benignity.