Which of the following is the most common functional pancreatic neuroendocrine tumor in MEN1 syndrome?

Explanation

## Pancreatic Neuroendocrine Tumors in MEN1 **Key Point:** Gastrinoma is the most common functional pancreatic neuroendocrine tumor in MEN1, occurring in approximately 40–60% of MEN1 patients with pancreatic involvement. However, non-functional tumors are even more common overall (60–70% of all pancreatic NETs in MEN1). **High-Yield:** In MEN1, gastrinomas are often multiple and located in the gastrinoma triangle (bounded by the junction of cystic and common bile ducts, junction of duodenum and pancreatic neck, and junction of pancreatic body and tail). They typically present with severe peptic ulcer disease and diarrhea (Zollinger–Ellison syndrome). ## Comparison of Pancreatic NETs in MEN1 | Tumor Type | Frequency in MEN1 | Clinical Presentation | Location | |------------|-------------------|----------------------|-----------| | **Gastrinoma** | 40–60% (functional) | Zollinger–Ellison syndrome, refractory PUD | Gastrinoma triangle (duodenum) | | **Insulinoma** | 10–30% | Hypoglycemia, Whipple's triad | Pancreatic body/tail | | **Non-functional** | 60–70% (overall) | Incidental finding, mass effect | Variable | | **VIPoma** | <5% | Secretory diarrhea, hypokalemia, achlorhydria | Pancreatic tail | | **Glucagonoma** | <1% | Necrolytic migratory erythema, hyperglycemia | Pancreatic tail | **Clinical Pearl:** MEN1-associated gastrinomas are often aggressive and multifocal, making them difficult to manage surgically. Proton pump inhibitors (PPIs) are the mainstay of medical management for acid hypersecretion. **Mnemonic: "Frequency of PNETs in MEN1"** — **G**astrinoma > **I**nsulinoma > **V**IPoma > **G**lucagonoma (GIVE in reverse order of rarity).