High-grade pancreatic intraepithelial neoplasia occurring in heterotopic pancreas of the gastric antrum: A case report.

RATIONALE: Heterotopic pancreas (HP) is a rare congenital developmental anomaly in which pancreatic tissue appears in a location other than the normal anatomical location of the pancreas. Most cases are no specific symptoms before surgery, and the pathological features are mostly benign, while malignant cases are rarely reported. HP with Pancreatic Intraepithelial Neoplasia (PanIN) is particularly rare in the literature. At present, the treatment of HP is controversial, especially when the lesion lacks obvious malignant characteristics, making it difficult to decide on surgical intervention.

PATIENT CONCERNS: A 47-year-old male was admitted to the hospital due to abdominal pain. He had been diagnosed with antral mass, cardiac mass, gastric retention, and chronic gastritis by gastroscopy in another hospital due to abdominal pain, which was managed nonsurgically. He denied any personal or family history of tumors.

DIAGNOSES: After admission, the physical examination was normal, and the laboratory examination showed that CA72-4 and triglyceride were slightly elevated, and the rest were normal. Endoscopic ultrasonography revealed a submucosal protrusion on the posterior wall of the antrum, located in the muscularis mucosa and submucosa, approximately 10.7 × 7.7 mm in size, with relatively clear boundaries, and containing glandular duct-like structures. Color Doppler ultrasound did not show obvious color blood flow echoes within the lesion. The remaining mucosal layer and outer membrane layer were smooth.It was considered to be a HP, without obvious high-risk features.

INTERVENTIONS: Given the patient's discomfort with abdominal pain, endoscopic submucosal dissection was performed, and a tissue sample was obtained for pathological testing.

OUTCOMES: Pathological findings revealed HP tissue with moderate to severe atypia, consistent with high-grade PanIN (PanIN-3).

LESSONS: This case illustrates that PanIN-3 can occur even in small HP lesions without obvious malignant imaging features. Therefore, for patients with significant symptoms or uncertain diagnoses, endoscopic submucosal dissection may be considered as a personalized diagnostic and therapeutic intervention to effectively mitigate potential complications and the risk of progression to pancreatic ductal adenocarcinoma .