Giant hepatic cystadenoma is extremely rare, and two cases were admitted to our department from 2007 to 2013, which are reported as follows. 1.Clinical data Case 1, male, 26 years old, aquatic. Epigastric mass with abdominal distension and abdominal pain for 2 years, aggravated for one week was admitted to the hospital. Epigastric distension and pain were persistent, without fever. One week ago, he suddenly felt nausea and vomiting, and the abdominal pain was not relieved after vomiting. Physical examination was slow with no yellowing of the skin and sclera. The mid-upper abdomen was distended without abdominal wall varicose veins. A huge mass was detected in the middle-upper abdomen, with smooth surface, tough texture, unclear boundary, compression pain, and poor mobility.CT scan: a huge oval low-density space-occupying lesion was seen in the right lobe of the liver, cystic, with segregation, with a CT value of 25HU, homogeneous density, and small punctate and slightly high-density calcified shadows, with a clear boundary and a size of about 32×22×18cm, and the neighboring organs were shifted by the compression. Enhanced CT scan, the huge cystic lesion in the middle and upper abdomen did not see obvious enhancement, and its capsule wall was obviously strengthened. A strengthened blood vessel was seen at the hepatic portal into the cystic wall. It suggests hepatic cystic space-occupying lesion. Color ultrasound: a huge cystic mass was seen in the abdominal cavity, with unclear morphology, unclear boundary, uneven internal echogenicity, no obvious blood flow signal, and liver echogenicity was faintly seen in the right upper abdomen.AFP was negative. During surgery, a huge mass was seen in the abdominal cavity, oval in shape, extending to the pelvis at the distal end, connecting with the right lobe of the liver and the left inner lobe at the base, with obvious envelope, and no adhesion with the gastrointestinal tract and the greater omentum. Puncture was performed to extract a coffee-colored, viscous, old and bloody fluid. A 1.0-cm decompression incision was made in the anterior wall of the mass, and about 10,500 ml. of fluid in the capsule was slowly aspirated over a 45-minute period. The cystic mass was bluntly and sharply separated from the hepatic tissue along the perimembranous surface of the mass, and the gallbladder and the mass, which were adherent to the mass, were completely resected. After resection of the mass, the tissue of the right lobe of the liver was seen to be markedly thinned and reduced by compression, and the left lobe was markedly compensated to increase in size. At the end of the operation, the cyst was incised, and the wall of the cyst was about 1-4 cm thick, with incomplete segregation within it, and no obvious papillary hyperplasia was seen. He was discharged from the hospital 3 weeks after surgery. Pathologic diagnosis: hepatic cystadenoma. Follow-up for 6 years, no recurrence of the mass was seen. Case 2, female, 58 years old, Buyei ethnicity. Abdominal mass was found for more than 10 years, and aggravated for 3 months. The right upper abdominal mass was first found to be the size of an egg, and had been slightly enlarged for more than 10 years, with occasional light swelling and discomfort. In the past 3 months, she realized that the mass was increasing rapidly, and the abdominal distension was getting heavier and heavier, with poor appetite, occasional chest tightness, and no vomiting. Physical examination: slow sick appearance, emaciation, middle-upper abdomen bulging, right middle-upper abdomen found a large mass, soft, light touch pressure pain, clear boundary, poor mobility. Color ultrasound: a huge cystic mass was seen in the abdominal cavity, with regular morphology, clear boundary, peritoneal membrane, uniform internal echogenicity, and no obvious blood flow signal.CT showed a huge cystic mass in the right lobe of the liver and the right middle-upper abdominal cavity, with a maximal dimension of 20.21×13.38×22cm, thin and uniform cystic wall, smooth boundary, and uniform internal density, with a CT value of 11-14 HU, and obvious deformation of the right kidney by pressure and left shift of the head of pancreas and intestinal lumen by push and pressure. The pancreatic head and intestinal lumen were pushed and shifted to the left. Intraoperative exploration revealed a huge liver cystic tumor in the abdominal cavity, the base of which was located in the right lobe of the liver, and the distal end was extended to about 8 cm below the umbilicus, with intact peritoneum and no adhesion with the surrounding tissues. The cyst was punctured to extract yellowish mixed fluid. After slightly enlarging the puncture point, about 3500 ml of fluid was aspirated from the cyst, which ended up as a dark brown turbid fluid. The cyst was completely resected along the pericardium. After resection of the cyst, the tissue of the right lobe of the liver was obviously thinned by pressure. At the end of the operation, the wall of the removed cyst was weighed and weighed about 500 g. The cyst was incised and the wall was about 1-3 mm thick, with no incomplete septum and no papillary hyperplasia. He was discharged from the hospital 2 weeks after surgery. Pathologic diagnosis:Hepatic cystadenoma with regenerative hyperplasia of hepatic nodes. Follow-up 3.5 years, no recurrence of the mass. Discussion Hepatic cystadenoma is very rare, mostly seen in women over 40 years old, and only one case was reported in children (1). One case in our group was a young male. The incidence of hepatic cystadenoma is about 1‰ of simple hepatic cysts, based on ultrasound and CT examination (1). Cong Wenming et al. reported only 4 cases of hepatic cystadenoma among 3160 cases of liver tumors (2). Li Hui et al. reported that hepatic cystadenoma accounted for 0.8% of intrahepatic benign tumors (3). The pathogenesis of this disease is still unclear, and it may originate from congenital abnormal intrahepatic bile ducts or misplaced germ cells, which is widely believed to be the former (1). Solid hepatic cystadenoma is also known as cystadenoma of the intrahepatic bile ducts. These tumors secrete large amounts of mucin-like mucus, and are therefore also called “mucin-hypersecretory” intrahepatic cholangiocarcinomas (4). Hepatic cystadenocarcinoma almost always develops from cystadenoma (1). Hepatic cystadenoma is usually a solitary, spherical, large, smooth and smooth cystic tumor with a diameter ranging from several centimeters to 25 centimeters. If the tumor is small, there are no symptoms and signs, while those with large tumors may have epigastric discomfort, vague pain, nausea, nausea, abdominal distension and so on. When the mass increases rapidly and the abdominal pain worsens rapidly, intracystic hemorrhage may occur. The diagnosis of this disease mainly relies on ultrasound and CT, and if ultrasound and CT find that there is a large bulge in the cystic cavity or calcification at intervals, malignant transformation should be highly suspected (1). This disease should be differentiated from simple hepatic cysts, hepatic echinococcal juvenile cysts, misshapen tumors, and hemangiomas. Hepatic cystadenoma should be completely removed surgically even if asymptomatic. Cyst openings and segmental resections are prone to recurrence. It is difficult to differentiate hepatic cystadenoma from hepatic cystadenocarcinoma preoperatively, and the treatment should be based on resection of the cyst or liver lobe. The cyst can be easily separated and resected by blunt or sharp separation along the gap between the peritoneum and normal liver tissue during surgery. When the gap between the cyst envelope and normal liver tissue is not very clear, the cyst should be separated on the side or within the liver tissue as much as possible; when the cyst is not large, regular hepatic resection should be performed as much as possible to reduce recurrence.