Case ReportFamilial Duodenal Somatostatinomatosis Not Associated With a Known Genetic SyndromeYu, Run MD, PhD∗; Rao, Jianyu MD†; Zhai, Jing MD, PhD‡; Hecht, J. Randolph MD∗; Pisegna, Joseph R. MD§ Author Information From the Departments of ∗Medicine †Pathology and Laboratory Medicine, UCLA David Geffen School of Medicine ‡Department of Pathology, Cedars-Sinai Medical Center §Department of Veterans Affairs, UCLA David Geffen School of Medicine, Los Angeles, CA. Received for publication March 26, 2022; accepted October 4, 2022. Address correspondence to: Run Yu, MD, PhD, Division of Endocrinology, Diabetes, and Metabolism, UCLA David Geffen School of Medicine, 200 Medical Plaza Dr, Ste 530, Los Angeles, CA 90095 (e-mail: [email protected]). The authors declare no conflict of interest. Pancreas 51(8):p 1056-1060, September 2022. | DOI: 10.1097/MPA.0000000000002126 Buy Metrics Abstract We report a father and his daughter who both had multiple somatostatinomas in the duodenal bulb without a known syndrome. The father, at age 68 years, was incidentally found to harbor 4 approximately 1.5-cm well-differentiated neuroendocrine tumors in the duodenal bulb. His preoperative somatostatin level was elevated. He underwent partial duodenectomy and regional lymph node dissection; one lymph node was positive for metastasis. One year postoperatively, a recurrence was found in the surgical bed; he was treated with octreotide for 2 years, which stabilized the recurrent tumor. Ten years postoperatively, the mucosa of his remaining duodenum was normal. His daughter, at age 53 years, was found to harbor multiple small neuroendocrine tumors in the duodenal bulb. Immunostaining of available specimens showed that the neuroendocrine tumors from the father and daughter both were strongly positive for somatostatin. Micronodules of somatostatin-expressing neuroendocrine cells were found in the parts of the specimens uninvolved with the tumors. Both patients exhibited no evidence of known syndromes associated with somatostatinoma. The daughter did not harbor mutations in 93 genes commonly found in genetic tumor syndromes. The 2 cases thus suggest a novel, autosomal dominant, genetic syndrome of familial duodenal somatostatinomatosis. Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.