A 40-year-old woman presents with recurrent hypoglycemic episodes relieved by food. Labs during an episode show serum insulin of 25 microU/mL with suppressed C-peptide negative for sulfonylurea metabolites. Imaging localizes a 1.2 cm lesion in the pancreatic tail. Which statement about this tumor is correct?
- A Over 70 percent are malignant at presentation with hepatic metastases
- B It secretes vasoactive intestinal peptide causing watery diarrhea and hypokalemia
- C It is the most common functioning pancreatic neuroendocrine tumor and is usually solitary and benign ✓
- D It is associated with markedly elevated serum gastrin and refractory peptic ulcers
Explanation
Insulinoma is the most common functioning pancreatic neuroendocrine tumor. It presents with the Whipple triad: hypoglycemic symptoms, plasma glucose below 50 mg/dL, and relief with glucose administration, along with inappropriately high insulin and A-peptide. Unlike other pancreatic neuroendocrine tumors, more than 90 percent of insulinomas are benign, solitary, and less than 2 cm, and only a minority are associated with MEN1. VIP secretion defines the WDHA syndrome of VIPoma, and hypergastrinemia with refractory ulcers defines gastrinoma (Zollinger-Ellison syndrome).
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.