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

## TL;DR

A patient with autoimmune gastritis developed multiple gastric cancers over time, highlighting the need for close monitoring in such cases.

## Contribution

This case report highlights the occurrence of synchronous and metachronous gastric cancers in a patient with autoimmune gastritis.

## Key findings

- A 78-year-old man with autoimmune gastritis developed multiple early gastric cancers.
- One cancer was synchronous, and another was metachronous, detected one year later.
- The case emphasizes the importance of monitoring for multiple primary cancers in AIG patients.

## Abstract

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.