Multicystic biliary hamartoma with extremely elevated CA19-9: a case report.

Multicystic biliary hamartoma (MCBH) is a rare cystic disease of the liver. We herein report a case of MCBH associated with extremely elevated levels of serum carbohydrate antigen (CA) 19-9. A 53-year-old man was referred to our hospital because of extremely elevated CA19-9 levels (more than 12,000 U/mL). Enhanced abdominal computed tomography and magnetic resonance imaging (MRI) revealed a multicystic tumor with a calcified wall in the left lobe of the liver, although no apparent intracystic nodule was detected. Because of the possibility of a malignant tumor, such as intraductal papillary neoplasm of the bile duct or cystadenocarcinoma, the patient underwent left hepatectomy. Based on the postoperative pathological findings, the lesion was diagnosed as MCBH. The serum CA19-9 level drastically decreased after surgery. We encountered a rare case of MCBH with extremely elevated CA19-9 levels.