Metachronous Occurrence of Mucosa-associated Lymphoid Tissue (MALT) Lymphoma in the Esophagus and Tonsillar Diffuse Large B-cell Lymphoma 18 Years After <i>Helicobacter pylori</i> Eradication for Gastric MALT Lymphoma

A 51-year-old man was diagnosed with gastric mucosa-associated lymphoid tissue (MALT) lymphoma after presenting with fold convergence on upper gastrointestinal radiography and nausea. He tested positive for Helicobacter pylori, and eradication therapy decreased the size of the gastric MALT lymphoma. Eighteen years later, whitish subepithelial lesions were discovered in the middle thoracic esophagus which were diagnosed to be esophageal MALT lymphoma. Six months later, the left tonsillar swelling was identified as diffuse large B-cell lymphoma (DLBCL). Complete remission was achieved after treatment with rituximab and chemotherapy. To our knowledge, this is the first reported case of metachronous gastric and esophageal MALT lymphoma with tonsillar DLBCL.