Synchronous duodenal mucosa-associated lymphoid tissue lymphoma and gastric cancer.

Duodenal mucosa-associated lymphoid tissue (MALT) lymphoma is an extremely rare tumor. Herein, we report multidisciplinary treatment of a patient with synchronous development of primary MALT lymphoma of the duodenum and gastric cancer. A 70-year-old woman was referred to our hospital for examination of a gastric cancer initially diagnosed by a local medical doctor. Esophagogastroduodenoscopy showed an elevated lesion with a central ulcer in the lower body of the stomach, and a partially whitish aggregated lesion in the descending portion of the duodenum. Histopathological examination of biopsy specimens from the gastric lesion showed moderately differentiated adenocarcinoma, and duodenal specimens showed low-grade MALT lymphoma composed of atypical lymphoid cells with a lymphoepithelial lesion. The patient underwent distal gastrectomy with regional lymph node dissection for the gastric cancer. Histological examination showed muscularis propria invading adenocarcinoma with two lymph node metastases. After operation, four courses of systemic rituximab treatment were administered for the MALT lymphoma, followed by adjuvant S-1 (tegafur/gimeracil/oteracil) chemotherapy for the gastric cancer. In the 4 months after operation, the patient was well with no evidence of recurrence. To the best of our knowledge, this is the second reported case of synchronous gastric adenocarcinoma and duodenal MALT lymphoma in the English literature.