A case of mucinous cystic neoplasm of the gallbladder.

The patient was a 70-year-old woman in whom examination revealed a high level of carbohydrate antigen 19-9. Abdominal ultrasonography and computed tomography (CT) revealed a multilocular cystic lesion compressing the gallbladder. CT indicated the presence of a multilocular cystic tumor (67 × 68 × 72 mm) in contact with the right hepatic lobe. Intraoperative findings indicated that the cyst diameter was 8.5 × 6.0 cm, and the cyst was continuous with the gallbladder. The gallbladder was resected along with the cyst. The cyst was multilocular and originated from the cystic duct and gallbladder wall. The cyst wall contained cuboidal to columnar mucin-producing epithelial cells and ovarian-like stroma (OS). The final diagnosis was mucinous cystic neoplasm (MCN) of the gallbladder with low-grade dysplasia. In the 2010 WHO classification of tumors of the digestive system, MCN have been newly defined as a type of hepatobiliary tract epithelial neoplasms. MCN of the gallbladder with OS is extremely rare. Only three cases have been published in the literature. The presence of OS is necessary for diagnosis of MCN.