Differential CT Features of Intraductal Biliary Metastasis and Double Primary Intraductal Polypoid Cholangiocarcinoma in Patients With a History of Extrabiliary Malignancy

Abstract

The purpose of this study was to discern clinical and imaging features for differentiating intraductal metastasis from double primary intraductal cholangiocarcinoma in patients with a history of extrabiliary malignant disease. Over a 10-year period, the cases of 14 patients with histopathologically proven intraductal metastasis (n = 8) or double primary intraductal cholangiocarcinoma (n = 6) who had a history of extrabiliary malignancy were identified. Two radiologists retrospectively reviewed CT (n = 14) and MR (n = 6) images for the size and appearance of the intraductal lesion, presence of a parenchymal mass, multiplicity, attenuation on arterial and portal phase images, and presence of calcification. Clinical findings such as the location of extrabiliary malignancy and presence of Clonorchis sinensis infestation also were recorded. Univariate tests were used to differentiate the two disease entities. Histopathologic confirmation was obtained by surgical resection (n = 12) or ultrasound-guided biopsy (n = 2). All intraductal metastatic lesions were of colorectal cancer, and all intraductal cholangiocarcinomas were associated with extracolonic malignant disease, including three cases of gastric cancer (p < 0.0001). All cholangiocarcinomas manifested themselves as purely intraductal masses, but five of the eight intraductal metastatic lesions were contiguous with parenchymal masses (p = 0.031). The appearance of the intraductal lesion was predominantly expansile in cases of metastasis (seven of eight cases) but not in cases of cholangiocarcinoma (one of six cases) (p = 0.026). Other findings were not statistically significant in differentiating the two disease entities. When an intraductal lesion is found in a patient with extrabiliary malignancy, the presence of a contiguous parenchymal mass, an expansile nature of the intraductal lesion, and a history of colorectal cancer may suggest the presence of intraductal metastasis rather than double primary intraductal cholangiocarcinoma.