From chronic diarrhea to diagnosis: unmasking rare giant gastrinoma

Abstract

Gastrinomas are rare neuroendocrine tumors, most commonly arising in the pancreas or duodenum and typically present with peptic ulcer disease and gastric acid hypersecretion. Atypical symptoms such as chronic diarrhoea and abdominal pain, along with partial response to proton pump inhibitors, may delay diagnosis and timely treatment. We report the case of a 35 years old male who presented with a one-year history of persistent watery diarrhoea and intermittent abdominal pain. Clinical examination revealed an abdominal mass and imaging demonstrated a giant pancreatic head lesion and biochemical analysis showed markedly elevated serum gastrin levels. Histopathology confirmed the diagnosis of gastrinoma. The unusually large tumor size, combined with an atypical presentation as chronic diarrhoea, highlights the diagnostic challenges associated with gastrinomas. This case underscores the importance of considering neuroendocrine tumors, including Zollinger–Ellison Syndrome (ZES), in the differential diagnosis of unexplained chronic diarrhoea and abdominal pain. Timely recognition and management are crucial to improving outcomes. Giant gastrinomas (>12 cm) with multifocality in the context of ZES have not been reported in the literature, making this case a unique addition.