RESUMEN
Zollinger-Ellison syndrome (ZES) is characterized by gastrin-secreting neuroendocrine tumors (gastrinomas) in the duodenum or pancreas. It is a rare condition, most patients are diagnosed between the ages of 20 and 50, and a higher incidence in men. Gastrinomas are associated with a high risk of malignancy and the diagnosis is confirmed by the secretin stimulation test and imaging studies such as octreotide scintigraphy. We present the case of a 24-year-old man who presented with melena, asthenia, adynamia and abdominal pain, in addition to a history of peptic ulcer. Laboratory tests revealed low levels of hemoglobin and elevated levels of gastrin. Endoscopy showed a giant ulcer and subsequent surgery revealed stomach-jejunum adhesions, gastric lesions and Meckel's diverticulum. Imaging studies confirmed neuroendocrine tumor activity in the pancreas. ZES leads to sustained hypergastrinemia, causing peptic ulcers and other digestive tract complications. Gastrinomas can arise from a variety of locations and can cause peptic ulcers, malabsorption, and diarrhea. Diagnosis requires elevated fasting serum gastrin levels and hypersecretion of gastric acid. Treatment involves discontinuation of proton pump inhibitors (PPIs) before diagnostic testing and surgical resection of tumors in suitable candidates. The diagnosis of ZES can be complicated due to the unreliability of the assays and the need for secretin testing. Surgical resection is recommended for sporadic gastrinomas without metastasis, while medical treatment may be necessary for postsurgical residual hyperacidity. Patients should undergo imaging studies for tumor localization and regular monitoring for complications and recurrences.