Morphological study of cholesterol hepatolithiasis. Report of three cases. Three cases of pure cholesterol intrahepatic stones are compared morphologically to those of calcium bilirubinate stones. Cholesterol stones were found in the intrahepatic bile duct of the left lateral lobe in two cases and in both the left lateral and the right posterior lobe in one. Although the chronic inflammatory reaction and fibrous thickening of bile duct wall were similar in both types of hepatolithiasis, the proliferation of intrahepatic periductal glands and the production of mucin were rather mild, compared to that is the liner containing calcium bilirubinate stones. Multiple intramural cholesterol calculi and cholesterin granulomas (cholesterin crystals surrounded by foreign-body giant cells) were found within the cystically dilated small bile duct branches and/or conduits of periductal glands. The calculi and granulomas were characteristic for cholesterol hepatolithiasis. These findings suggest that the formation of the cholesterol stones differs from that of calcium bilirubinate stones; the perturbation of factors influencing cholesterol nucleation in the hepatic bile may be related to the changed microenvironment of the intrahepatic bile ducts, which is followed by the formation of cholesterol stones. 