[Detection of monoclonality of gastric MALT lymphoma using PCR method and its clinicopathological application]

Twenty cases of H. pylori-related gastric lymphoproliferative disorders including 12 cases of MALT lymphoma (Grade 5 after Wotherspoon, et al), 6 of suspicious of MALT lymphoma (Grade 4), and 2 of active chronic gastritis (Grade 3) were studied. Using the nested PCR method, paraffin-embedded gastric biopsy specimens of these 20 cases were investigated whether or not monoclonal IgH rearrangement could be demonstrated in infiltrating lymphoid cells. Monoclonal IgH rearrangement was recognized in 6 of 12 MALT lymphomas, but in other 14 cases including 6 of MALT lymphomas the monoclonality was not recognized. The result showed the sensitivity was 50% and the specificity was 100% with this method. Follow-up study after eradication of H. pylori was performed on 6 cases of MALT lymphoma which had showed the monoclonality before, using the same method. The monoclonality disappeared in 5 of 6 and histology showed a complete remission. In the remaining one case the monoclonality was yet demonstrated and lymphoma cells were histologically recognized. Thus, this method is very useful to assess not only the histological diagnosis of MALT lymphoma but also the effectiveness after treatment.