Severe Recurrent Gastrointestinal Bleeding and Diagnostic Dilemmas in Zollinger-Ellison Syndrome: A Case Report.

Zollinger-Ellison Syndrome (ZES) is a rare condition caused by gastrin-secreting neuroendocrine tumours (gastrinoma) that induce excessive gastric acid production, leading to severe peptic ulcer disease (PUD) and gastrointestinal (GI) complications. Its nonspecific presentation often delays diagnosis, increasing the risk of life-threatening outcomes. We report the case of a 53-year-old man with chronic gastroesophageal reflux disease and long-standing unexplored diarrhoea who presented with worsening abdominal pain and severe diarrhoea. Laboratory tests showed acute kidney injury, and CT revealed gastric wall thickening and a hyperdense nodule at the gastroduodenal junction, raising suspicion for ZES. Despite proton pump inhibitor (PPI) therapy, he developed recurrent upper GI bleeding requiring intensive care unit admission. Hormonal and imaging studies confirmed ZES, and he underwent antrectomy with lymphadenectomy. Postoperatively, he experienced further GI bleeding managed with over-the-scope clip (OTSC®) haemostasis and gastroduodenal artery ligation. Pathology confirmed a well-differentiated neuroendocrine tumour (pT2N1, G1). One year later, he remained asymptomatic with no evidence of recurrence. This case illustrates the diagnostic and therapeutic challenges of ZES, underscoring the risks associated with PPI withdrawal during evaluation and the need for multidisciplinary management. Recurrent GI bleeding in ZES requires a coordinated approach integrating medical, endoscopic, and surgical therapies. Early recognition is essential to prevent severe complications, and a high index of suspicion is warranted in patients with refractory PUD, chronic diarrhoea, or unexplained GI bleeding.