Sclerosing cholangitis induced by formaldehyde solution injected into the biliary tree of rats.

Sclerosing cholangitis has been reported after surgical treatment of hydatid disease of the liver and has been hypothetically attributed to the caustic effect of the parasiticide solution injected into the cyst and diffusing into the biliary tree through a cystic-biliary fistula. In this experimental study, we showed that, in rats, injection into the biliary tract of 20% hypertonic saline solution or 2% formaldehyde solution, the most commonly used scolicidal solutions, was followed by lesions of the biliary epithelium. As compared with 20% hypertonic saline solution, the 2% formaldehyde solution caused more severe lesions of the biliary epithelium and, in addition, induced the development of sclerosis. This experimental study confirms the deleterious effect of scolicidal solutions to the biliary epithelium, shows that their effect is mainly related to the causticity of the scolicidal solution, and indicates that intracystic injection of 2% formaldehyde solution should be abandoned.