Abstract
Introduction: The caterpillar or Moynihan's hump is characterized by a tortuous right hepatic artery running proximal and/or parallel to the cystic duct and predisposes to a small and/or short cystic artery. Case presentation: A 24-year-old woman with no relevant clinical history underwent a laparoscopic cholecystectomy for cholelithiasis; during the procedure a caterpillar or Moynihan's hump was identified. Clinical discussion: Moynihan's hump varies between 1% and 13% of all cases. Conclusion: Biliary and arterial variations are more frequent than we think, so an anatomical knowledge, critical view of safety; represent a fundamental rule, increasing the safety of the surgical procedure.