A0660 - Ampullary Somatostatinoma: Diagnostic Challenge and Associations

Albina Joldoshova, MD¹, Selma Z. Elsarrag, MS², George Van Buren, MD², Peyman Dinarvand, MD², Shilpa Jain, MD^2
1Baylor College of Medicine, Sugar Land, TX; ²Baylor College of Medicine, Houston, TX

Introduction: Duodenal somatostatinoma is an exceedingly rare neuroendocrine tumor (NET) originating from the delta cells of the pancreas or enterochromaffin cells of the duodenum. While pancreatic tumors mostly produce clinical symptoms due to excess somatostatin production, duodenal tumors are often asymptomatic or can present with biliary obstruction symptoms such as abdominal pain, jaundice, or cholelithiasis. We report a subtle case of somatostatinoma arising from an ampulla.

Case Description/Methods: 64-year-old male started experiencing sudden onset shortness of breath, melena, intermittent abdominal pain, and anorexia a few months after being involved in an uneventful motor vehicle collision.

Imaging displayed 2 cm ampullary nodule protruding into the duodenum. The upper endoscopy revealed non-obstructing mass, biopsy of which showed well differentiated NET. The Whipple resection unveiled 2.5 cm subepithelial lesion, infiltrating the sphincter of Oddi and duodenal muscularis propria. Histologically, lesions were composed of small nests of cells with stippled chromatin arranged in a glandular pattern. Focal psammoma bodies within the glandular lumina were appreciated. Immunohistochemically tumor cells were positive for synaptophysin, chromogranin, CAM-5.2, and somatostatin, confirming the diagnosis of somatostatinoma (Figure). Three peripancreatic lymph nodes were positive for metastatic carcinoma.



Discussion: According to The World Health Organization criteria, most duodenal somatostatinomas are malignant, and hence prompt diagnosis is crucial, but can be challenging particularly in non-functional ones as in our case. Seeing psammoma bodies in histology are diagnostic clues. Somatostatin analogs such as Octreotide and Lanreotide are used as first-line agents after confirmation. Ampullary tumors may require genetic evaluation since their Neurofibromatosis type 1 and other syndromic associations.



Disclosures:


Albina Joldoshova, MD¹, Selma Z. Elsarrag, MS², George Van Buren, MD², Peyman Dinarvand, MD², Shilpa Jain, MD². A0660 - Ampullary Somatostatinoma: Diagnostic Challenge and Associations, ACG 2022 Annual Scientific Meeting Abstracts. Charlotte, NC: American College of Gastroenterology.