Helicobacter pylori-negative gastric mucosa-associated lymphoid tissue lymphoma - A clinicopathologic and molecular study with reference to antibiotic treatment

BACKGROUND. The majority of gastric mucosa-associated lymphoid tissue (MALT) lymphoma develops in Helicobacter pylori-associated chronic gastritis. Little is still known regarding the clinicopathologic features of gastric MALT lymphoma not associated with H. pylori infection. METHODS. One hundred thirty-seven patients with gastric MALT lymphoma, in whom H. pylori status was evaluated using at least both serology and histology, were enrolled. Clinical, histopathologic, and molecular findings were compared between H. pylori-negative group (n = 12; 9%) and H. pylori-positive group (n = 125; 91%). t(11;18)(q21;q21) was investigated by reverse-transcription polymerase chain reaction and interphase fluorescence in situ hybridization. RESULTS. In cases without diffuse large B-cell lymphoma (DLBCL) component, H. pylori-negative lymphomas located more frequently in the proximal stomach (70%), less frequently appeared as superficial type (40%), and frequently invaded the submucosa or beyond (70%). Histologically, lymphoepithelial lesions (57%), lymphoid follicles (43%), and background mucosal atrophy (50%) in the H. pylori-negative group were less frequent than in the H. pylori-positive group (91%, 93%, and 100%, respectively). The frequencies of t(H;18)(q21;q21) (100%) and BCL10 nuclear expression (100%) in the H. pylori-negative group were significantly higher than in the H. pylori-positive group (2% and 27%, respectively). Response to antibiotic treatment was observed not only in the H. pylori-positive group (75%), but also in the H. pylori-negative group (2 of 7 patients, 29%). In cases with a DLBCL component, such differences were not observed between the 2 groups. CONCLUSIONS. H. pylori-negative gastric MALT lymphoma is characterized by frequent t(11;18) (q21;q21). Antibiotic treatment should be considered also for this disease, although cases with t(11;18)(q21;q21) may need additional strategies.