Duodenal neuroendocrine tumor and the onset of severe diabetes mellitus in a US veteran

Objective: Neuroendocrine tumors are neoplasms derived from endocrine cells, most commonly occurring in the gastrointestinal tract. Duodenal neuroendocrine tumors are rare tumors averaging 1.2-1.5 cm, and most are asymptomatic. Common presentation is abdominal pain, upper gastrointestinal bleed, constipation, anemia, and jaundice. Methods: An adult, Black, male patient with newly diagnosed diabetes mellitus presented to the emergency department with elevated liver function test and fatigue. Results: Magnetic resonance cholangiopancreatography demonstrated a large obstructing mass (3.6 cm x 4.4 cm x 3 cm) within the second and third portions of the duodenum at the ampulla. Esophagogastroduodenoscopy demonstrated an ulcerated duodenal mass that was biopsied. Immunohistochemical stains were positive for synaptophysin, chromogranin B, and CK7. Chromogranin A was in normal range. Post-Whipple procedure demonstrated a 5.5 cm x 4.1 cm x 2.9 cm duodenal mass with invasion of the subserosal tissue of the small intestine, a mitotic rate of 2 per high-power field, and antigen Ki-67 of 2%-5%. Conclusion: This case raises the question as to if the patient developed diabetes mellitus due to the tumor size and location or if the new onset of diabetes was coincidental. This case also demonstrates the importance of a proficient history and physical.