LOW-GRADE GASTRIC B-CELL LYMPHOMA OF MUCOSA-ASSOCIATED LYMPHOID-TISSUE - CLINICOPATHOLOGICAL ANALYSTS OF 19 CASES

Low-grade gastric B-cell lymphoma of mucosa-associated lymphoid tissue type (MALToma) is a recently recognized disease entity. We report the clinicopathologic features of 19 patients with MALToma in Tai wan. Th e 19 patients included eight men and 11 women, ranging in age from 26 to 77 years, with a mean age of 58.8 years. Most complained of abdomin al pain or gastrointestinal bleeding. The endoscopic and gross feature s of the gastric lesions revealed erosion (flat type), ulceration (dep ressed type), cobblestone appearance or abnormal gastric folds (elevat ed type), mimicking chronic gastritis, ulcer or early gastric carcinom a. Typical histopathologic features included lymphoepithelial lesion a nd extensive mucosal infiltration of centrocyte-like cells in all case s. Clonality analysis of the variable-diversity-joining region of the immunoglobulin gene by semi-nested polymerase chain reaction demonstra ted monoclonality in 72% of the cases. Helicobacter pylori bacilli (H. pylori) could be identified on histologic sections in 15 cases (78.9% ); the serologic test for H. pylori was positive in 12 of 13 patients tested (92%). In six patients receiving triple therapy (amoxicillin, b ismuth subcitrate and metronidazole), five showed significant histolog ic regression with eradication of H. pylori 4 to 6 months after the st art of treatment; one patient showed persistent lesions and presence o f H. pylori However, persistence of residual lymphoid cells and monocl onality of the immunoglobulin gene, could still be demonstrated in fou r cases. Of nine patients treated with surgery or chemotherapy, two di ed: one due to concomitant gastric carcinoma and the other one due to sudden apnea. No recurrence was observed in the remaining seven patien ts. The remaining four patients were lost to follow-up. Our experience confirmed that gastric MALToma is a low-grade neoplastic process. The dramatic response of gastric MALToma to anti-H. pylori treatment sugg ests that H. pylori infection is closely related to the pathogenesis o f low-grade gastric MALToma. However, long-term follow-up is mandatory due to the persistence of the monoclonality of the immunoglobulin gen e in the residual lymphoid cells after treatment.