Monoclonality in Helicobacter pylori-positive gastric biopsies: an early detection of mucosa-associated lymphoid tissue lymphoma

Mucosa-associated lymphoid tissue (MALT) is not present in healthy gastric mucosa, but it can develop in sites of long-persisting inflammation and is connected with the development of MALT lymphoma. A monoclonal lymphocyte population is one of the characteristics of such lymphomas. In this study we analyzed gastric biopsies (formalin fixed and paraffin embedded or frozen) in 93 patients with dyspepsia accompanied by Helicobacter pylori infection. We applied PCR and single-cell immunocytochemistry to detect the clonality of the gastric B-cell population. Immunocytochemistry performed on 33 frozen biopsies showed two samples with monoclonal pattern. PCR analysis of immunoglobulin heavy-chain (IgH) gene rearrangements revealed two monoclonal populations out of 161 biopsies from 60 patients. We conclude that PCR analysis was the most sensitive method, which gave us insight into the nature of the earliest stage of MALT lymphoma in gastric biopsies.