Endoscopic ultrasound in the evaluation of gastric small lymphocytic mucosa-associated lymphoid tumors.

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Low-grade, small lymphocytic lymphomas of the mucosa-associated lymphoid tissue (MALT) have recently been shown to be associated with Helicobacter pylori infections. Regression of these tumors has been reported with antibiotic therapy. Here we evaluate endoscopic ultrasound (EUS) as on objective method to evaluate pretreatment disease and posttherapy response. We retrospectively reviewed 20 patients initially diagnosed elsewhere with MALT lymphoma. All patients had their initial endoscopic biopsies (EGDs) reviewed at Memorial Sloan-Kettering Cancer Center (MSKCC). All patients had EUS performed at the time of consultation and on completion of therapy if treated at our center. Antral biopsies were stained with a modified Steiner preparation to determine infection by H pylori. Gastric low-grade lymphoma was confirmed in 16 of 20 patients; 11 of 16 had previously received antibiotic therapy for biopsy-positive H pylori infection. All gastric lymphomas had an abnormal EUS: eight with discrete tumor masses and eight with gastric wall infiltration (submucosa, n = 4; muscularis propria, n = 3; serosa, n = 1). On completion of lymphoma treatment with chemotherapy, radiotherapy, or surgery, 11 of 16 patients underwent follow-up EUS. Five patients received care elsewhere and did not return for posttreatment EUS. The gastric wall was normal with no evidence of disease on EUS-guided biopsy in eight of 11 patients. The remaining three patients had abnormal gastric walls. One was biopsy-negative and two had residual lymphoma. Four patients were found to have benign lymphoid aggregates in association with H pylori on initial EGD and EUS biopsies. All four patients were previously untreated with antibiotics. EUS showed prominent mucosa, but no significant findings within the gastric wall. EUS appears useful to stage objectively and evaluate therapeutic outcome in the management of gastric, low-grade MALT lymphomas. It also helps to distinguish benign lymphoid aggregates from lymphoma associated with H pylori infection. EUS findings may have a significant impact on assessment and therapeutic recommendations.