A Case of Synchronous and Metachronous Gastric Neoplasms Associated With Autoimmune Gastritis.

Patients with autoimmune gastritis (AIG) are reported to be associated with an increased risk of developing gastric neuroendocrine and gastric tumors. Again, those with cancer are shown to be at risk of developing multiple primary cancers within two months of the first primary cancer (synchronous cancers) or more than two months afterward (metachronous cancers). A 78-year-old man was diagnosed with early gastric cancer and referred to our hospital for endoscopic treatment. Curative resection was performed with endoscopic submucosal dissection (ESD), which also revealed AIG in the background gastric mucosa. Follow-up esophagogastroduodenoscopy (EGD) performed three months later revealed an erythematous, superficial depressed lesion and a whitish, superficial flat lesion in the greater curvature of the gastric angle, which established the diagnosis of early gastric cancers. Curative resection was again performed with ESD. Retrospectively, one of these lesions was found to be a synchronous gastric cancer. A follow-up EGD performed one year later newly detected a 5 mm adenoma in the gastric angle, which was treated endoscopically as a metachronous lesion. Thus, the present case highlights the need to watch for multiple primary cancers when treating patients with cancer, particularly those with AIG.