A 45-year-old woman with known MEN1 syndrome undergoes biochemical screening. She is found to have elevated fasting gastrin levels with a secretin stimulation test showing a paradoxical rise in gastrin >200 pg/mL. Which pancreatic tumor is responsible?

• A Insulinoma
• B Glucagonoma
• C VIPoma
• D Gastrinoma (Zollinger-Ellison syndrome) ✓

Explanation

Gastrinoma (Zollinger-Ellison syndrome) is the second most common functional pancreatic NET in MEN1 after insulinoma. The secretin stimulation test is the gold standard: intravenous secretin normally suppresses gastrin, but in gastrinoma there is a paradoxical rise of ≥200 pg/mL above baseline. Insulinoma presents with hypoglycemia and high insulin; glucagonoma causes necrolytic migratory erythema; VIPoma causes secretory diarrhea (Verner-Morrison syndrome).

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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