Gastrinomas are neuroendocrine tumors (NETs), usually located in the duodenum or pancreas, that secrete gastrin and cause a clinical syndrome known as Zollinger–Ellison syndrome (ZES). A large number of gastrinomas develop in the pancreas or duodenum, with near-equal frequency, and approximately 10% arise as primary neoplasms in lymph nodes of the pancreaticoduodenal region (gastrinoma triangle).Most gastrinomas are sporadic (75–80%), whereas approximately 20–25% are associated with multiple endocrine neoplasia type 1 (MEN-1). Over 50% of gastrinomas are malignant and can metastasize to regional lymph nodes and liver. One fourth of gastrinomas are related to multiple endocrine neoplasia type 1, Zollinger–Ellison syndrome, peptic ulcer disease. Signs and symptoms
Gastrinoma in the early stages will have signs and symptoms of indigestion or similar to irritable bowel disease (IBD) such as:

Hypergastrinemia
Refractory or recurrent peptic ulcers involving duodenum
Chronic diarrhea
Generalized cancer symptoms
Abdominal pain
Gastrointestinal bleeding
Obstruction of intestine
Weight loss/poor appetite
Anemia (Due to vitamin B12 malabsorption, and bleeding)
Hematemesis
Gastroesophageal reflux disease
Esophageal complications (Barretts esophagus, esophagitis, stricture formation)
Vomiting
Steatorrhea

Pathophysiology
Gastrin is secreted by the G cells. G cells are primarily found in the pyloric antrum but can also be found in the duodenum and the pancreas. The primary function of gastrin is to induce the release of hydrochloric acid (HCl) from the parietal cells located in the fundus of the stomach. Parietal cells are responsible for hydrochloric (HCl) secretion along with intrinsic factor that binds to vitamin B12 and helps with its uptake in the terminal ileum. Other functions of gastrin include stimulating the growth of gastric mucosa and gastric motility and promoting gastric emptying.
Obstruction  may refer to:

Places
Obstruction Island, in Washington state
Obstruction Islands, east of New Guinea

Medicine
Obstructive jaundice
Obstructive sleep apnea
Airway obstruction, a respiratory problem
Recurrent airway obstruction
Bowel obstruction, a blockage of the intestines. Gastric outlet obstruction
Distal intestinal obstruction syndrome
Congenital lacrimal duct obstruction
Bladder outlet obstruction

Politics and law
Obstruction of justice, the crime of interfering with law enforcement
Obstructionism, the practice of deliberately delaying or preventing a process or change, especially in politics
Emergency Workers (Obstruction) Act 2006

Science and mathematics
Obstruction set in forbidden graph characterizations, in the study of graph minors in graph theory
Obstruction theory, in mathematics
Propagation path obstruction
Single Vegetative Obstruction Model

Sports
Obstruction (baseball), when a fielder illegally hinders a baserunner
Obstructing the field

See also
The Five Obstructions, a 2003 film
USS Obstructor, an American minelayer ship used in World War II