Zollinger-Ellison Syndrome (Gastrinoma)

DEFINITION:

A syndrome characterized by ulceration of the upper jejunum, hypersecretion of gastric acid, and nonbeta islet cell tumors of the pancreas
Unlike typical peptic ulcer disease, this syndrome is often progressive, persistent, and frequently life-threatening; See also Bowel- GI Endocrine Tumors (Chapter 2.16)

EPIDEMIOLOGY:

Most between 30-50 y/o; Male > Female
U.S. incidence is ˜0.1-1% of all patients with duodenal ulcer (PUD)
- May be an underestimate since symptoms similar to NSAID and H. Pylori disease and symptoms controlled with antisecretory drugs

ETIOLOGIES:

Gastrin has been identified as the humoral agent responsible for the syndrome
- Gastrin may be the link between the increased risk of carcinoids with ZES and Chronic Type A Gastritis
Acid hypersecretion is defined as basal acid output of gastrin >10 mmol/hr

PATHOPHYSIOLOGY:

Caused by a gastrinoma, a benign or malignant tumor of gastrin-secreting G cells
- Located: pancreas 60-80% (non-beta islet cell tumor) or duodenum 25-35% (G-cell hyperplasia – over functioning of gastric G cells)
- Derived from pluripotent endocrine cells; Tumors are well-differentiated
May be sporadic or associated with MEN-1
- 75% occur as a sporadic syndrome, occurring as an isolated condition
- 25% association with multiple endocrine neoplasia type 1 (MEN-1): Parathyroid, Pituitary, Pancreas (ZES); Autosomal dominant