Gastrinomas are uncommon neuroendocrine neoplasms (NENs) that secrete the hormone gastrin in excess, and result in the classic Zollinger–Ellison syndrome (ZES). First described in 1955, ZES includes the triad of diffuse gastroduodenal ulcerations, gastric acid hypersecretion, and pancreatic nonbeta islet tumors [1]. When Robert Zollinger and Edwin Ellison described their findings at the American Surgical Association meeting in 1955, they did not know gastrin was the culprit until Gregory and Tracy demonstrated that gastrinoma tumor extract increased acid secretion in dogs in a manner similar to that of antral gastrin extract [2]. Preoperative determination of gastrin was not feasible until gastrin was first measured by radioimmunoassay in 1968, which ushered in the “modern” era of ZES diagnosis [3].