Solitary cystic dilation of the intrahepatic bile duct: morphology of two autopsy cases and a review of the literature.

Solitary cystic dilation of intrahepatic bile ducts with neither extrahepatic biliary anomalies nor renal lesions has been reported previously in only 11 cases. We report two cases which were found as a result of postmortem cholangiography of 149 livers at autopsy. Case 1 had a cystic dilation measuring 1.2 cm in diameter in the left lateral superior area duct. Case 2 showed a cystic dilation measuring 1.0 cm in diameter in the left lateral segment duct. Histologically, the walls of the dilated ducts consisted of fibrous wall with proliferation of periductal mucous glands in both cases. The dilated and adjacent bile ducts in case 2 also contained tiny brown pigment stones and biliary sludge, suggesting that this bile duct lesion is important in the formation of intrahepatic calculi by providing a site for bile stasis and mucous hypersecretion.