Gastrinoma (Zollinger-Ellison Syndrome)

• • Peptic ulcer disease—often severe

  • Gastric hypersecretion

  • Elevated serum gastrin with simultaneous acid in the stomach

  • Gastrin producing non-B islet cell tumor of the pancreas or duodenum (gastrinoma)

Epidemiology

• • 95% pancreatic, 60% non-B islet cell carcinomas; 25% solitary adenomas; 10% hyperplasia or microadenomas

  • 5% are due to solitary submucosal gastrinomas in the first or second portion of the duodenum

  • Rarely found in the antrum or ovary

  • About 33% associated with multiple endocrine neoplasia type 1 (MEN 1)—usually multiple benign gastrinomas

  • Those without MEN 1 (sporadic cases) usually have solitary gastrinomas that are often malignant

  • The tumors may be as small as 2-3 mm; in about 33% of cases, the tumor cannot be located at laparotomy

  • Histologic pattern is similar for benign and malignant tumors

  • -Diagnosis of cancer can be made only with findings of metastases or blood vessel invasion

Symptoms and Signs

• • Symptoms are principally a result of peptic ulcer disease from acid hypersecretion

  • Ulcer symptoms are often refractory to antacids or H2 blocking agents.

  • Some patients have severe diarrhea from the large amounts of acid entering the duodenum, which can destroy pancreatic lipase and produce steatorrhea, damage the small bowel mucosa, and overload the intestine with gastric and pancreatic secretions

Laboratory Findings

• • Hypergastrinemia (> 500 pg/mL) in the presence of acid hypersecretion (> 15 mEq H+ per hour).

  • Gastrin levels > 5000 pg/mL or chains of hCG in the serum usually indicates established metastasis

  • Secretin provocative test for borderline gastrin values (200-500 pg/mL)

  • -A rise in gastrin level of >150 pg/mL within 15 minutes is diagnostic

Imaging Findings

• • Esophagogastroduodenoscopy: Usually shows ulceration in the duodenal bulb, distal duodenum, or proximal jejunum

  • CT or MRI: Often detects pancreatic tumors.

  • Somatostatin-receptor scintigraphy: Very sensitive for detection of gastrinoma primary and metastatic sites

  • Failure of other methods: Localize with intra-arterial secretin test (infusion of secretin into the artery supplying a functional gastrinoma causes an increase in hepatic vein gastrin levels)

• • Serum gastrin levels should be measured in any patient with suspected gastrinoma or ulcer disease severe enough to warrant consideration of surgical treatment

  • Discontinue H2 receptor blocking agents, omeprazole, or antacids several days before measuring gastrin level (may increase serum gastrin concentrations)

  • Measure serum calcium (common association with hyperparathyroidism)

Rule Out

• • Hypergastrinemia and gastric acid hypersecretion also seen in gastric outlet obstruction, retained antrum, and antral cell hyperplasia

  • -Differentiate with secretin test

  • Pernicious anemia, atrophic gastritis, gastric ulcer and postvagotomy state may cause a rise in serum gastrin with decreased gastric acid

• • Signs and symptoms of peptic ulcer disease

  • Endoscopic evidence of peptic ulceration

  • Measurement of serum gastrin

  • Confirmation of acid hypersecretion

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