Familial Duodenal Somatostatinomatosis Not Associated With a Known Genetic Syndrome.

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.