Hepatic mucinous cystic neoplasm, also called biliary cystadenoma of the liver, is a rare neoplasm, with fewer than 500 cases reported in the literature. The vast majority of these tumors occur in women, generally in the fifth and sixth decades. The most striking feature of this cystic tumor is the presence of ovarian-type stroma underneath the cystic-lining epithelium. Importantly, the epithelium can demonstrate high-grade dysplasia and progress to carcinoma. Radiological studies do not reliably distinguish carcinoma. Therefore, complete excision is recommended, and extensive pathological sampling of these lesions is critical in the determination of prognosis. The histological differential diagnosis includes simple solitary (simple) biliary cyst, cystic dilatation of the intraductal papillary neoplasm of the bile duct, intrahepatic biliary developmental anomalies (Caroli disease), endometrial cyst, echinococcal cyst (hydatid cyst), and ciliated hepatic foregut cyst. Immunohistochemical studies including estrogen receptor, progesterone receptor, and inhibin are useful in highlighting the ovarian-type stroma and establishing the diagnosis, especially in cases with hyalinized stroma. Immunohistochemical studies for cytokeratin 7 (CK7), CK8, CK18, CK19, CA-19-9, and AE1/AE3 highlight the epithelium. In some cases, the mucinous nature of the epithelium is prominent and will stain for alcian blue and mucicarmine. Identification and proper sampling of these tumors are important because of their potential to harbor invasive carcinoma.