Endoscopic submucosal dissection combined surgery for the treatment of ectopic gastric mucosa and ectopic pancreas in muscularis propria and serosal layer of the stomach: A rare case report and review of the literature.

Rationale: Ectopic gastric mucosa (EGM) and ectopic pancreas (EP) in the stomach is a rare congenital anomaly. No research on the coexistence of EGM and EP in the stomach has been found. However, several studies have shown canceration of EGM outside the stomach and EP. Active surgical treatment may be necessary. This paper introduces a new case of ectopic gastric mucosa and ectopic pancreas in muscularis propria and serosal layer of the stomach and which were ultimately removed by endoscopic submucosal dissection combined surgery.

Patient Concerns: The patient was a 25-year-old male. Upper gastrointestinal endoscopy showed a subepithelial lesion in gastric antrum.

Diagnoses: Postoperative pathology confirmed a diagnosis of EGM and EP.

Interventions: Enhanced computed tomography scan and endoscopic ultrasonography showed a submucosal tumor. Then endoscopic submucosal dissection was performed, during which a lesion was observed on the anterior wall of the stomach near the pylorus. This lesion invades the muscularis propria of the stomach and the large lesions near the pylorus may lead to pyloric obstruction. Considering these situations comprehensively, the patient ultimately underwent surgical resection of gastric lesion and partial gastrectomy.

Outcomes: After 3 months of follow-up, the patient was recovering well and no recurrence of the lesion was found so far.

Lessons: EGM along with EP in the stomach is a rare condition. Due to its rarity, there was a lack of sufficient data support for its treatment and prognosis. Due to the EGM and EP may become cancerous, clinical attention should be paid to it. In this study, we present a new case report of EGM along with EP in the stomach and review the existing literature to explore treatment options for it.