Accessory liver lobe attached to the gallbladder wall preoperatively detected by ultrasonography: A case report

•An accessory liver lobe is a rare anomaly of the liver.•An accessory liver lobe is usually asymptomatic and incidentally detected during surgery or autopsy in most cases.•An accessory liver lobe should be resected in order to prevent complications and malignant transformation.•Ultrasonography is useful in case of accessory liver lobe for preoperative diagnosis.

IntroductionAn accessory liver lobe is a rare developmental abnormality, which is often not diagnosed preoperatively, and is usually detected incidentally during abdominal surgery. This condition is often asymptomatic; here, we report on a case where the accessory liver lobe was diagnosed preoperatively using ultrasonography.Case presentationA 59-year-old woman presented to our hospital with right upper abdominal pain. An abdominal ultrasonography indicated the presence of gallbladder debris and an accessory liver lobe. She underwent laparoscopic cholecystectomy and resection of the accessory liver lobe without any complications.DiscussionAn accessory liver lobe is a rare anomaly of the liver. It is typically asymptomatic and is detected incidentally during surgery or autopsy in most cases. However, we diagnosed the accessory liver lobe using ultrasonography. An accessory liver lobe can occasionally result in complications, such as bleeding, portal vein obstruction, or malignant transformation to hepatocellular carcinoma.ConclusionAn accessory liver lobe should be resected to prevent complications and malignant transformation. Ultrasonography is useful for preoperative diagnosis in cases with an accessory liver lobe.