The patient is a 41-year-old female of Mongolian ethnicity, who came to the clinic for 5 months after 7 years of cholecystectomy and biliary-intestinal anastomosis with ultrasound findings of bile duct dilatation. On examination: stable vital signs, no yellow staining of skin and sclera, 15 cm old surgical scar visible under the right rib cage, mild pressure pain in the right upper abdomen, no rebound pain and muscle tension, negative Murphy’s sign, no palpation of liver and spleen and gallbladder, mild percussion pain in the liver area, no mobile turbid sounds, normal bowel sounds. Ultrasound of the abdomen showed that: 3.8 cm×5.8 cm group-like strong echogenic and anechoic areas were seen in the left inner lobe of the liver, with irregular morphology and clear borders, and no colored blood flow signal was seen; the inner diameter of the left intrahepatic bile duct was 0.5 cm, and the inner diameter of the intrahepatic segment of the extrahepatic bile duct was 1.0 cm. MRI examination showed: dilated intra- and extrahepatic bile ducts, and malignant occupancy could not be excluded. Abdominal enhancement CT return showed: multiple enlarged intrahepatic bile ducts were seen in the left lobe of the liver, the left hepatic duct was significantly dilated and soft tissue deformation was seen within it, the right hepatic duct and common bile duct were dilated; enhancement scan showed moderate enhancement of the soft tissue lesion in the left hepatic duct, and the possibility of malignancy was considered. Diagnosis: left intrahepatic Caroli disease; bile duct cancer? Hepatocellular carcinoma? After cholecystectomy and bile duct jejunostomy. The right upper abdomen was examined by transrectal abdominal skin incision, which revealed: no ascites in the abdominal cavity, slightly enlarged liver with bile-like changes and hard texture, and an enlarged left liver with a hard mass of about 5 cm in diameter could be palpated. The extrahepatic bile ducts and jejunal collaterals were visible in the hilar region on autopsy, and the bile ducts were obviously dilated. The pancreas was soft and without nodule-like changes; the spleen was normal in size and there was no mass. There were no obvious abnormalities in the stomach and intestines, and the pelvis and uterine adnexa were normal. The left hepatectomy, biliary-enteric anastomosis and bile duct jejunostomy Roux-Y anastomosis were performed. Postoperative gross pathology: bile duct dilatation with a maximum circumference of 7 cm and rough bile duct wall with raised plaques. Microscopic pathology: hypodifferentiated adenocarcinoma of the bile duct, mostly mucinous adenocarcinoma, tumor tissue infiltrating the whole layer with infiltration of nerves. Eleven months after this operation, the patient underwent another caesarean section due to recurrent right upper abdominal pain for 5 months: there was no fluid or ascites in the abdominal cavity, dense adhesions in the liver, abdominal wall, greater omentum and anastomosis, and dense nodular masses were seen at the junction of the right hepatic diaphragm and dirty surface and bile-intestinal anastomosis, with a fish-like cut surface, and one biopsy was taken. The patient was discharged from the hospital 10 days after surgery. After follow-up, the patient died at home 5 months after the second discharge due to multiple organ failure. The exact etiology of Caroli disease, also known as intrahepatic cystic dilatation of the bile ducts, is not well understood, and most scholars believe that Caroli disease is a congenital disorder due to chromosomal recessive inheritance, probably caused by congenital structural weakness of the bile ducts or sympathetic dysplasia. it was first described in detail by the French scholar Caroli in 1958 and has since been defined as Caroli disease by scholars at home and abroad [ 1]. Patients with this disease are characterized by 1 phasic or columnar dilatation of the intrahepatic bile ducts; 2 a marked predisposition to cholelithiasis, cholangitis and liver abscesses, Caroli divided this disease into two types, type I and type II, also known as simple type, which is mostly associated with intrahepatic bile duct stones and has clinical manifestations of recurrent biliary tract infections; type II, also known as periportal fibrosis type, which is mostly accompanied by congenital hepatic fibrosis, with hepatosplenomegaly, This type is characterized by portal hypertension and upper gastrointestinal bleeding. In China, Caroli’s disease is generally prevalent in type I. According to the distribution of cysts in the liver and related pathological changes, Academician Huang Zhiqiang classified the disease into the following four types [1]: Type I: simple or limited, often with a lobar distribution without hepatic fibrosis; it is further divided into two subtypes: peripheral (I a) and central (I b). Type II: diffuse type, often with hepatic fibrosis. Type III: diffuse type with segmental distribution of intrahepatic cysts. Type IV: combined with cystic dilatation of the common bile duct. Clinical symptoms appear due to the formation of intrahepatic bile duct stones and biliary tract infection in most cases after long-term intrahepatic bile storage, mainly manifesting as recurrent abdominal pain, fever or jaundice, which may develop into liver abscess, subdiaphragmatic abscess or sepsis if left untreated. Direct imaging by PTC or ERCP can show clear images of bile duct dilatation and provide a clear basis for diagnosis. The surgical treatment of Caroli’s disease is mostly done by choledochotomy and common bile duct or common hepatic duct jejunostomy at home and abroad. Due to the high rate of malignancy, local lesions should be removed, and if the lesion is limited to the liver lobe, hepatectomy can be performed.