Metachronous gastric MALT lymphoma and early gastric cancer: is residual lymphoma a risk factor for the development of gastric carcinoma?

Background: Helicobacter pylori plays a major role in the pathogenesis of primary gastric MALT lymphoma (GML) and gastric carcinoma. The occurrence of these two diseases metachronously in a same patient is a rare event. Patients and methods: Gastric biopsies and gastrectomy resection specimens of four patients who developed GML and early gastric cancer (EGC) were analysed by morphology, immunohistochemistry and molecular biology. Results: Four patients (three males and one female; mean age 48 years) were diagnosed with GML. Helicobacter pylori infection was observed in three cases. Two patients had localized disease (stages IE and IIE, respectively) and were treated with H. pylori eradication therapy followed by an alkylating agent for one patient. Two patients had disseminated disease (stage IV), and were treated with an alkylating agent. Three cases were t(11;18) positive. All patients achieved initially complete lymphoma remission. Long-term endoscopic surveillance detected an EGC at the same location as the lymphoma in all patients at a mean time of 9.5 years (range 2.5–17 years) after lymphoma diagnosis. Gastrectomy specimens showed residual GML in all cases. Conclusion: Prolonged residual GML could constitute an additional risk factor for the development of gastric carcinoma. Long-term endoscopic surveillance is mandatory in patients treated conservatively for gastric MALT lymphoma.