Zollinger-Ellison syndrome overview

# Overview
Patients with Zollinger-Ellison syndrome may experience abdominal pain and diarrhea. The diagnosis is also suspected in patients without symptoms who have severe ulceration of the stomach and small bowel, especially if they fail to respond to treatment. Gastrinomas may occur as single tumors or as multiple, small tumors. About one-half to two-thirds of single gastrinomas are malignant tumors that most commonly spread to the liver and lymph nodes near the pancreas and small bowel. Nearly 25 percent of patients with gastrinomas have multiple tumors as part of a condition called multiple endocrine neoplasia type I (MEN I). MEN I patients have tumors in their pituitary gland and parathyroid glands in addition to tumors of the pancreas. Development of Zollinger-Ellison syndrome is the result of increased levels of gastrin due to an existing gastrinoma in the duodenum or pancreas. Zollinger-Ellison syndrome must be differentiated from gastric antrum syndrome, antral G-cell hyperplasia, peptic ulcer, gastroesophageal reflux disease (GERD), and hypergastrinemia. The incidence of gastrinoma, which can cause Zollinger-Ellison syndrome, is approximately 0.5-2 persons per 100,000 individuals worldwide. Pharmacologic medical therapies for Zollinger-Ellison syndrome include proton pump inhibitors, H2-receptor antagonists, chemotherapy, and hormonal therapy. Effective measures for the primary prevention of Zollinger-Ellison syndrome include genetic testing, if family history presents.

# Historical Perspective
In 1955, Zollinger and Ellison published their seminal paper on gastrinomas wherein the Zollinger-Ellison syndrome was first discussed.

# Pathophysiology
Development of Zollinger-Ellison syndrome is the result of increased levels of gastrin due to an existing gastrinoma in the duodenum or pancreas.

# Causes
The cause of Zollinger-Ellison syndrome has not been identified. However, 25 to 30 percent of gastrinomas, which can cause Zollinger-Ellison syndrome, are caused by  multiple endocrine neoplasia type 1 (MEN1).

# Differentiating Zollinger-Ellison syndrome from other Diseases
Zollinger-Ellison syndrome must be differentiated from gastric antrum syndrome, antral G-cell hyperplasia, peptic ulcer, gastroesophageal reflux disease (GERD), and hypergastrinemia.

# Epidemiology and Demographics
The incidence of gastrinoma, which can cause Zollinger-Ellison syndrome, is approximately 0.05-0.2 per 100,000 individuals worldwide. About 25 to 30 percent of gastrinomas are caused by  multiple endocrine neoplasia type 1 (MEN1). Zollinger-Ellison syndrome is a disease that tends to affect the middle-aged adult population. Males are more commonly affected with Zollinger-Ellison syndrome than females.

# Natural History, Complications and Prognosis
If left untreated, patients with Zollinger-Ellison syndrome may progress to develop abdominal pain, diarrhea, and heartburn. Common complications of Zollinger-Ellison syndrome include upper gastrointestinal bleeding, anemia, and duodenal ulcer perforation. Prognosis is generally good, and the 5 and 10-year survival rate of patients with Zollinger-Ellison syndrome is approximately 94% and 75%, respectively.

# Diagnosis

## History and Symptoms
Symptoms of Zollinger-Ellison syndrome include diarrhea, odynophagia, nausea, and hematemesis .

## Physical Examination
Common physical examination findings of Zollinger-Ellison syndrome include epigastric tenderness, pallor, and jaundice.

## Laboratory Findings
An elevated concentration of fasting serum gastrin level and secretin stimulation test may be helpful in the diagnosis of Zollinger-Ellison syndrome.

## Abdominal CT
Abdominal CT scan may be helpful in the diagnosis of Zollinger-Ellison syndrome caused by gastrinoma. Gastrinomas are frequently multiple and often extrapancreatic (90% located in the gastrinoma triangle). Thus, they can be difficult to locate. For this reason, multiphase contrast enhanced thin slice cross-sectional imaging is ideal. Findings on Abdominal CT scan suggestive of gastrinoma include clearly defined, well-enhanced mass.

## Abdominal MRI
Abdominal MRI may be helpful in the diagnosis of Zollinger-Ellison syndrome caused by gastrinoma. Findings on abdominal MRI suggestive of Zollinger-Ellison syndrome include solitary lesion or multiple lesions.

## Abdominal Ultrasound
Abdominal ultrasound may be helpful in the diagnosis of Zollinger-Ellison syndrome caused by gastrinoma.

## Other Imaging Studies
Endoscopic ultrasound and  somatostatin receptor scintigraphy (SRS) (octreotide scan)  may be helpful in the diagnosis of Zollinger-Ellison syndrome caused by gastrinoma.

## Other Diagnostic Studies
Other diagnostic studies for Zollinger-Ellison syndrome include upper endoscopy, which demonstrates erosive esophagitis, thickened gastric folds, and antral erosions.

# Treatment

## Medical Therapy
Pharmacologic medical therapies for Zollinger-Ellison syndrome include proton pump inhibitors, H2-receptor antagonists, chemotherapy, and hormonal therapy.

## Surgery
The feasibility of surgery depends on the stage of gastrinoma causing Zollinger-Ellison syndrome at the time of diagnosis. However, all patients diagnosed with Zollinger-Ellison syndrome with no metastasis should be offered surgical exploration and resection.

## Primary Prevention
Effective measures for the primary prevention of Zollinger-Ellison syndrome include genetic testing, if family history is positive.

## Secondary Prevention
Secondary prevention strategies following Zollinger-Ellison syndrome include surgical resection of gastrinoma to prevent malignant trasformation and distant metastasis.