Background: Mucosa-associated lymphoid tissue (MALT) lymphoma involving multiple organs is not well characterized.
Methods: To obtain a better understanding of gastric MALT lymphoma with multiple organ involvement, we compared Helicobacter pylori infection status; response to eradication therapy; prevalence of genetic abnormality, including t(11;18)(q21;q21); and clonality of tumor cells between patients with gastric MALT lymphoma with and without multiple organ involvement.
Results: Of 54 patients with only gastric involvement, 51 were positive for H. pylori (94.4%), whereas only 3 of 9 patients with multiple organ involvement had the infection (33.3%). Among those who received eradication therapy, the remission rate in patients with only gastric involvement was significantly higher than that in patients with multiple organ involvement (71.4% vs 33.3%; P < 0.05). The positive rate of API2-MALT1 fusion transcripts was significantly greater in patients with multiple lesions with either single or multiple organ involvement than in those with a single gastric lesion (71.4% vs 12.5%; P < 0.05), but 2 of 2 patients with multiple gastric lesions had the fusion transcripts. Of 5 patients with multiple organ involvement tested for clonality of the CDR3 region, distinct clones were detected in lymphoma lesions in different organs in 3 patients, whereas the identical clone was present in the different lesions in the remaining 2 patients.
Conclusions: Gastric MALT lymphoma with multiple organ involvement is often associated with API2-MALT1 fusion transcripts. Moreover, H. pylori infection is rare in patients with multiple organ involvement as compared to those with only gastric involvement. Patients with gastric MALT lymphoma with multiple organ involvement who are positive for H. pylori are resistant to eradication therapy.