Zollinger-Ellison Syndrome

Zollinger-Ellison syndrome (ZES) is caused by autonomous gastrin secretion from neuroendocrine tumors (gastrinomas), typically located in the gastrinoma triangle (cystic duct, second-third portion of duodenum, pancreatic neck). Approximately 60-80% are sporadic and 20-25% occur in MEN1 (multiple endocrine neoplasia type 1).

Clinical presentation is dominated by recurrent and refractory peptic ulcers (often atypical locations such as distal duodenum or jejunum), severe esophagitis, abdominal pain, secretory diarrhea (gastric acid inactivates pancreatic enzymes), steatorrhea, and weight loss. Up to 60% of gastrinomas are malignant with hepatic metastases at diagnosis.

Diagnosis requires fasting serum gastrin >10x upper normal with gastric pH <2, secretin stimulation test (gastrin rise >120 pg/mL), and tumor localization with somatostatin receptor PET-CT (DOTATATE), endoscopic ultrasound, and CT-MRI. MEN1 screening with calcium, PTH, and pituitary imaging mandatory. Management is high-dose PPI to control acid hypersecretion, surgical exploration with intraoperative ultrasound for sporadic localized disease, and systemic therapy (somatostatin analogs, everolimus, sunitinib, peptide receptor radionuclide therapy) for metastatic disease.