# A Synchronous Gastric Intramural Metastasis from Multiple Gastric Cancers

## TL;DR

This case report describes a rare instance of intramural metastasis in a patient with multiple gastric cancers.

## Contribution

The novelty lies in documenting a rare case of gastric intramural metastasis in the context of multiple primary gastric cancers.

## Key findings

- Intramural metastasis was confirmed in a submucosal tumor-like lesion.
- The patient had multiple gastric cancers staged as pT2N1M0, Stage IIA.
- The patient remains recurrence-free after surgery and adjuvant chemotherapy.

## Abstract

Although intramural metastasis has been reported in esophageal cancer, it is extremely rare in gastric cancer. In this report, we describe a case of gastric intramural metastasis in a patient with multiple gastric cancers.

A 49-year-old woman was referred to our hospital after abnormalities were detected during barium screening. Computed tomography revealed gastric wall thickening with some areas of calcification and enlargement of the lesser curvature of the lymph nodes. Upper gastrointestinal endoscopy identified the following: (1) a type 2 tumor (sig-muc-tub1) on the posterior wall of the gastric angle, (2) a type 2 tumor (muc) on the anterior wall of the lower gastric body, and (3) a 0-IIc lesion (tub1) on the posterior wall of the middle gastric body. Additionally, (4) a submucosal tumor-like elevation with erosion was noted on the greater curvature of the gastric angle; however, no cancer cells were detected in this lesion. Given the patient's young age and the presence of multiple lesions, laparoscopic total gastrectomy with D2 lymphadenectomy was performed. The postoperative course was uneventful, and the patient was discharged on postoperative day 10. Postoperative pathological examination confirmed that lesions (1)–(3) were gastric cancers, staged as pT2N1M0, Stage IIA. However, lesion (4) showed no cancer cells in the mucosal layer but demonstrated mucinous carcinoma in the submucosal layer, which was diagnosed as gastric intramural metastasis. Based on the Japanese gastric cancer guidelines, postoperative adjuvant chemotherapy with S-1 was planned. At 4 months postoperatively, the patient is undergoing adjuvant chemotherapy and remains recurrence-free.

We encountered a case of gastric intramural metastasis in a patient with multiple gastric cancers. Intramural metastasis in gastric cancer is extremely rare, and further accumulation of cases is essential to elucidate its clinicopathological features. We hope that this case report will contribute to the accumulation of cases and enhance our understanding of the characteristics of intramural metastasis in gastric cancer.