A Rare Presentation of Benign Vaterian Adenomyoma With High-Grade Adenomatous Dysplasia.

Benign neoplasms of the ampulla of Vater are infrequently encountered: overall adenomas account for <10% of ampullary neoplasms; adenomyomas are even rarer. This report describes the case of a 78-year-old woman who presented with epigastric pain, elevated lipase and transaminases with imaging notable for acute pancreatitis, and intrahepatic and common bile duct biliary dilatation without choledocholithiasis. A 25-mm ampullary mass was identified during esophagogastroduodenoscopy with endoscopic ultrasound. The mass was determined to be suitable for endoscopic mucosal resection, which was subsequently performed. Histological examination confirmed a benign submucosal Vaterian adenomyoma with overlying mucosal high-grade glandular adenomatous dysplasia. This presentation is exceptionally rare in clinical practice.