CureusMultiple Incidental Pancreatic Neuroendocrine Tumors in a Patient with Suspected Duodenal Papillary Adenocarcinoma: A Case Report

⚠️ Small Study / Early Comparative Evidence

Periampullary tumors can present with overlapping clinical and radiographic findings that complicate preoperative diagnosis. This case describes a patient whose presumed ampullary adenocarcinoma was ultimately identified as multifocal well-differentiated pancreatic neuroendocrine tumors following surgical resection.

Clinical Considerations

• Endoscopic biopsy and EUS-FNA were both non-diagnostic despite persistent clinical suspicion for malignancy.
• Final pathology revealed multiple well-differentiated G1 pancreatic neuroendocrine tumors rather than ampullary adenocarcinoma.
• The tumors demonstrated a Ki-67 index of 1% and were staged pT1N0M0 following resection.
• Multifocal PNETs may raise concern for MEN1 syndrome, although genetic testing was not performed.

Practice Applications

• Recognize limitations of tissue sampling in selected periampullary lesions.
• Interpret negative biopsy results within the broader clinical context.
• Consider hereditary syndromes when multifocal neuroendocrine tumors are identified.
• Integrate pathology, imaging, and clinical findings when assessing diagnostic uncertainty.