Zollinger-Ellison Syndrome and Gastrinoma: Distinct Entities

Introduction to ZES and Gastrinoma

Zollinger-Ellison Syndrome (ZES) is a clinical syndrome characterized by hyperchlorhydria-induced peptic ulcer disease and chronic diarrhea, resulting from gastrin hypersecretion produced by a gastrinoma, a gastrin-secreting neuroendocrine tumor, according to the American Gastroenterological Association 1

Severe peptic ulceration refractory to standard therapy is a common presentation of ZES, as noted by the American College of Gastroenterology 2
Chronic diarrhea occurs in approximately 50% of patients with ZES at diagnosis, as reported by the National Institute of Diabetes and Digestive and Kidney Diseases 1, 2
Gastroesophageal reflux disease refractory to standard therapy is another manifestation of ZES, according to the American Gastroenterological Association 1, 2
Epigastric pain lasting years despite acid-suppressive therapy is reported in 70% of patients with ZES at diagnosis, as noted by the American College of Gastroenterology 2
Weight loss is also a symptom of ZES, as reported by the National Institute of Diabetes and Digestive and Kidney Diseases 1

Gastrinomas have a high rate of malignancy, with metastases developing in 60% of patients, correlated to primary tumor size, according to the National Cancer Institute 1
Gastrinomas are associated with multiple endocrine neoplasia-1 syndrome, as reported by the Endocrine Society 3, 4

Biochemical confirmation of ZES requires fasting serum gastrin >1000 pg/mL combined with gastric pH <2, as recommended by the American Gastroenterological Association 5
Gallium-68 radiotracers with positron emission tomography is currently the standard for tumor localization, according to the Society of Nuclear Medicine and Molecular Imaging 1
Endoscopic evaluation using EUS has sensitivity up to 83% for pancreatic gastrinomas, as reported by the American Society for Gastrointestinal Endoscopy 1