Background & Aims:

Traditional serrated adenomas (TSAs) are a distinct subtype of gastrointestinal polyps with serrated glandular architecture and complex histologic features, predominantly reported in the distal colorectum. TSAs of the duodenum, and particularly the ampulla of Vater, are extremely rare, with fewer than ~40 cases documented. While colorectal TSAs are common, upper gastrointestinal TSAs account for <1% of small bowel polyps. Despite their scarcity, ampullary TSAs carry significant malignant potential, with up to 28.6% associated with invasive carcinoma. Histologically, they show serrated architecture and ectopic crypt foci, sometimes with elongated nuclei and eosinophilic cytoplasm. Due to limited cases, evidence on optimal management and outcomes is scarce. We report a periampullary TSA with high-grade dysplasia successfully treated with endoscopic papillectomy.

Methods:

A 64-year-old woman with obesity and gastroesophageal reflux disease underwent upper endoscopy in an external center, revealing a 2-cm ampullary lesion; biopsies showed adenoma with low-grade dysplasia (LGD). Contrast-enhanced CT confirmed a 2-cm periampullary lesion with mild billiary dilatation, without biliary duct involvement or deep invasion. We repeated endoscopy, revealing an enlarged papilla of Vater, polypoid with a villous surface, suggestive of papillary adenoma. Given the lesion was well-circumscribed,without invasive signs, and showed no alarming characteristics, en bloc endoscopic papillectomy was performed with prophylactic biliary and pancreatic stenting. Histopathology and immunohistochemistry were performed on the resected specimen. Follow-up endoscopies were scheduled at 1, 3, and 12 months.

Results:

The procedure was completed without complications, and the patient was discharged after 48 hours. Histopathology confirmed a traditional serrated adenoma with high-grade dysplasia and clear margins. Follow-up endoscopies demonstrated complete mucosal healing and no recurrence at 1 year.

Conclusion:

Ampullary TSAs are exceptionally rare lesions with significant malignant potential. This case demonstrates that endoscopic papillectomy is a safe and effective organ-preserving treatment for well-circumscribed lesions without ductal or deep invasion. High-grade dysplasia underscores the importance of structured long-term endoscopic surveillance. Reporting such cases enhances understanding of periampullary TSAs and supports evidence-based endoscopic management in carefully selected patients.