Synchronous adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma in a single stomach

Synchronous gastric adenocarcinoma and primary gastric mucosa-associated lymphoid tissue (MALT) lymphoma are rare, and the characteristics of these tumors are still unclear.

Histology of endoscopic and surgical specimens of 6012 gastric adenocarcinoma and 25 primary gastric MALT lymphoma cases were reviewed.

Five cases of synchronous tumors were found among 25 primary gastric MALT lymphoma patients (20.0%) and among 6012 gastric adenocarcinoma patients (8.3%). Helicobacter pylori was detected only in two cases (40.0%) of these five synchronous cases. In only one case, two types of malignant cells were mingled each other as a colliding tumor. In other four cases, two pathologies coexisted separately. These two types of malignant tumors were not distinguished by endoscopic or gross findings.

Although gastric adenocarcinoma coexists with MALT lymphoma at a relatively high frequency, synchronous carcinoma can be misinterpreted as a multifocal separated lesion of MALT lymphoma owing to their macroscopic resemblance. Therefore, gastric MALT lymphoma patients should be carefully examined by endoscopy, and any suspicious area must be biopsied considering the possibility of coexisting adenocarcinoma. In addition, etiologies other than H. pylori should be considered in these synchronous tumors.