Cholangiocarcinoma in association with Thorotrast exposure

Thorotrast is a colloidal suspension of thorium dioxide that was used as an intravascular contrast agent until the 1950's. It is retained by the reticuloendothelial system, and because it emits densely ionizing radioactivity thorium dioxide it is carcinogenic. Two patients with prior thorium dioxide exposure diagnosed with cholangiocarcinoma and recently treated at the Massachusetts General Hospital are presented. Radiology, treatment, pathologic findings, and relevant literature are discussed.