[Thorotrastosis and thorotrast carcinoma of the kidney. A differential diagnostic problem]

Thorotrast deposts produce intense fibrosis and it is not uncommon for malignant tumors to arise in such cases. Thus for example, renal carcinoma was observed 35 years after administration of Thorotrast. Such carcinomas may be difficult to diagnose in time because of radiogenic nephritis. In the light of experience with a 55-year old man, the reason for delayed carcinoma diagnosis was lack of formation of tumor nodes due to intense fibrosis resulting in diffuse and canalicular tumor spread. Hence it is obvious that angiography may not be diagnostic in such cases.