Hepatoma induced by thorium dioxide (thorotrast).

A case of hepatoma induced by thorium dioxide (Thorotrast) is reported. The literature concerning neoplasia associated with this agent is reviewed, with emphasis on the long latent period before the development of these tumours and the equally long latent period which preceded the recognition of their iatrogenic nature.In particular, this report is intended to illustrate the diagnosis of such tumours on radiological and histological findings, provided that one is aware of their existence and familiar with the distribution and appearance of thorium dioxide deposits in the tissues. Such a diagnosis can be made without a history of thorium dioxide administration, which often may not be available.