gastrinoma

A gastrinoma is a rare neuroendocrine tumor that secretes gastrin, a hormone that stimulates gastric acid production. Most gastrinomas arise in the pancreas or the duodenum, though they can occur elsewhere. A substantial portion of gastrinomas are associated with multiple endocrine neoplasia type 1 (MEN1). When gastrin excess leads to acid hypersecretion and multiple, refractory peptic ulcers, the condition is referred to as Zollinger-Ellison syndrome (ZES).

Pathophysiology and clinical features include excessive gastrin causing marked gastric acid production, which can produce peptic ulcers beyond the usual locations, along with gastritis, gastroesophageal reflux, abdominal pain, and diarrhea. Ulcers may be numerous, aggressive, and difficult to heal, and symptoms often persist despite standard anti-ulcer therapy.

Diagnosis rests on a combination of laboratory tests and imaging. A markedly elevated fasting serum gastrin level with a low gastric pH is highly suggestive; a level typically above 1000 pg/mL supports the diagnosis. The secretin stimulation test can help confirm gastrinoma when levels are equivocal. Imaging studies such as CT or MRI locate primary tumors, while somatostatin receptor imaging (for example, Ga-68 DOTATATE PET or octreotide scans) detects primary and metastatic disease. Endoscopy assesses ulceration. Evaluation for MEN1 is also recommended.

Treatment aims to control acid secretion and manage tumor burden. High-dose proton pump inhibitors effectively suppress acid. Localized tumors may be cured by surgical resection. Metastatic or unresectable disease is managed with somatostatin analogs (to control symptoms and hormone release), and liver-directed therapies or systemic therapies as indicated. Prognosis depends on stage at diagnosis and presence of metastases.