BACKGROUND Biliary cystadenoma (BCA) and biliary cystadenocarcinoma (BCAC) are often confused with other intrahepatic cystic diseases.

AIMS The aims of this study were to investigate predictive factors of biliary cystic tumor (BCT) and clinical characteristic of BCAC.

METHODS We retrospectively reviewed preoperative diagnoses, overall characteristics and postoperative outcome of 20 BCTs and 19 cystadenoma-mimicking simple cysts that were pathologically confirmed.

RESULTS Comparing with atypical simple cysts, symptoms, left-lobe cyst, thick wall, septation, mural nodule, bile duct dilatation and an increase of serum alkaline phosphatase were associated with BCTs. However, on multivariate analysis, mural nodule, left-lobe cyst, and an increase of serum alkaline phosphatase were significantly frequent in BCTs with odds ratios of 75.5, 13.8, and 33.0, respectively. Among the 20 BCTs, seven BCACs were diagnosed. The characteristics of BCACs were mural nodule (P<0.01), intrahepatic cyst debris (P<0.01), and bile duct dilation (P=0.04). Cystic fluid analysis provided no significant differences between BCT and simple cyst. After fine needle aspiration cytology of BCTs, all except one BCAC with atypical cell showed nonspecific findings. After complete surgical excision (97.4% of patients), only one patient with BCAC had recurrence during 29 months of follow-up period.

CONCLUSION In hepatic cysts with mural nodule, left-lobe cyst or increment of serum alkaline phosphatase seem to be indicative of BCTs in the diagnosis of suspicious hepatic cyst. Intracystic debris, bile duct dilation, and mural nodule may be suggestive clinical features of malignancy in BCTs.