[A Case of Cystic Biliary Hamartoma with a Difficult Preoperative Diagnosis].

Intrahepatic bile duct dilatation was detected in a 63-year-old man based on abdominal ultrasonography. The computed tomography and magnetic resonance imaging scans showed an intrahepatic cystic lesion in the hilar bile duct that led to intrahepatic bile duct dilatation. As a result, intraductal papillary neoplasm of the bile duct(IPNB)was suspected. Moreover, the intrahepatic bile duct dilatation was confirmed by endoscopic retrograde cholangiopancreatography(ERCP). Biliary and brushing cytology indicated that the cystic lesion was class Ⅱ and class Ⅲ, respectively. Radiological imaging test did not rule out the possibility of a malignant lesion. Hence, a radical left hepatectomy was performed. Histopathological examination of the resected specimen indicated that it was a non-malignant cystic biliary hamartoma. Cystic biliary hamartoma or the von Meyenburg complex is a relatively rare disease. Although this disease is categorized as benign, differential diagnosis between benign and malignant forms is difficult, and this is an important clinical issue.