Computed tomography of biliary cystadenoma and biliary cystadenocarcinoma.

INTRODUCTION Biliary cystadenoma (BCA) and biliary cystadenocarcinoma (BCAC) are rare biliary ductal neoplasms of the liver. This study aims to describe the computed tomography (CT) findings of these neoplasms and to distinguish between both entities. METHODS We retrospectively reviewed the CT findings of five patients with proven BCA and seven patients with proven BCAC at our institution from July 2000 to August 2006. The CT parameters were analysed, including number, size, location, and characteristics of the cystic lesion: presence and number of internal septation, calcifications and enhanced mural nodule. RESULTS All 12 patients had a solitary, large well-defined intrahepatic cystic lesion. Lesions in all five patients with proven BCA (100 percent) and six patients with proven BCAC (86 percent) had a multilocular appearance. The remaining patient with proven BCAC had a unilocular lesion. Smooth, thin septa and walls were found in five patients with BCA (100 percent). The enhanced mural nodule at the septum or wall was identified in seven patients with BCAC (100 percent) but was not found in the BCA patients (p-value is less than 0.001). The other parameters including size, location and number of septa had no statistically significant differences between BCA and BCAC. CONCLUSION BCA and BCAC should be considered in the differential diagnosis, when a solitary large well-defined multilocular intrahepatic cystic lesion is detected in a middle-aged woman. The presence of an enhanced mural nodule is the most important finding to suggest BCAC.