Mucinous Cystic Neoplasm of the Cystic Duct: A Rare Location of a Rare Entity.

Mucinous cystic neoplasms (MCNs) are uncommon cystic lesions that arise in the liver and biliary system (MCN-LBS) and the pancreas (MCN-P) and rarely arise from the extrahepatic biliary system. Histologically, these lesions are defined by the presence of variably mucin-producing epithelium with ovarian-like, hypercellular mesenchymal stroma. Herein, we present a case of extrahepatic MCN-LBS in a 51-year-old woman. This lesion arose from the cystic duct and was removed via laparoscopic cholecystectomy. Histologic examination confirmed the diagnosis. To our knowledge, this is the third case report of an MCN-LBS arising from the cystic duct in the English literature. In this article, we review clinical and histologic characteristics of MCNs and present two other reports of MCN-LBS of the cystic duct.