Thorotrast-induced hepatosplenic neoplasia: CT identification

Despite discontinuation of its use in the 1950s, the consequences of Thorotrast usage continue to be recognized. In a review of plain film and CT findings of 20 cases of Thorotrast exposure, 15 of 17 patients demonstrated Thorotrast accumulation in the liver and spleen on plain films. Typically, this appeared as regions of trabeculated increased density within the liver. The spleen was of normal or decreased size and often demonstrated a finely punctate pattern of opacification. Only two malignancies could be suggested on plain film alone: one hepatic and one splenic. Five patients with hepatic malignancies underwent CT examinations: three with cholangiocarcinoma, one with angiosarcoma, and one with hepatocellular carcinoma. No specific criteria could be established to distinguish among these lesions, as each neoplasm appeared as relatively low-density mass(es). Two cases of splenic angiosarcoma appeared as low-density filling defect(s) in the otherwise opaque spleen, one case primary and the other metastatic from the liver. CT was superior to plain radiography in detecting and characterizing Thorotrast distribution and any superimposed malignancy. In addition to periodic liver function tests, screening CT of patients exposed to Thorotrast might detect hepatic neoplasms at an operable stage.