T(11;18)(q21;q21) in gastric MALT lymphoma and diffuse large B-cell lymphoma of Chinese patients.

T(11;18)(q21;q21) occurs at variable frequencies in mucosa-associated lymphoid tissue (MALT) lymphomas of different sites. In gastric MALT lymphoma, it occurs in 30% cases and the translocation positive tumours are frequently at advanced stages and do not respond to Helicobacter pylori eradication. Intriguingly, t(11;18)(q21;q21) has been observed only rarely in mucosal diffuse large B-cell lymphomas (DLBCL), despite that at least a proportion of these tumours are believed to be the result of transformation of an MALT lymphoma. We previously examined t(11;18)(q21;q21) in gastric MALT lymphoma of Chinese in Taiwan and found the translocation in one of the three transformed MALT lymphomas studied. To extend this observation, we have examined t(11;18)(q21;q21) in a large cohort of gastric lymphomas of Chinese in China including 39 MALT lymphomas (12 with high-grade components) and 53 DLBCL by reverse transcription and PCR. Of these cases, RNA samples extracted from 36 MALT lymphomas including 10 cases with high-grade component and 46 DLBCL were adequate for detection of the translocation as judged by control RT-PCR of a house-keeping gene. T(11;18)(q21;q21) was found in 8/36 (22%) MALT lymphomas and 1/46 (2%) DLBCL. None of the MALT lymphoma with high-grade component showed t(11;18)(q21;q21). Our results suggest that t(11;18)(q21;q21) occurs only occasionally in transformed MALT lymphoma.