Intrahepatic biliary stones: imaging features and a possible relationship with ascaris lumbricoides

Intrahepatic (IH) biliary stones are common in East Asia as part of a disease known as Oriental cholangiohepatitis (OCH). At a hospital serving non-Oriental communities, 40 patients were diagnosed on ultrasound (US) during an 8-year period as having IH stones. Follow-up showed that the diagnosis was false in three cases. In the 37 patients with IH stones, 33 conventional retrograde cholangiograms were done; 26 underestimated the IH abnormalities or missed them entirely. Computed tomography (CT) was done in 15 of these 37 patients; the attenuation of the stones was found to be only slightly above that of liver. The evidence that Ascaris lumbricoides was the cause of IH stones in our patients was that: they came mainly from communities in which A. lumbricoides infestation is virtually universal at some stage of childhood, and none from communities in which it is infrequent; their average age was younger than that of patients with conventional gall-stones, fitting with the fact that infestation is predominantly in childhood; A. lumbricoides is the only parasite in our region that invades the biliary system; the histories of the first 12 of the 37 patients had been investigated for intestinal infestation, and were all positive; and 12 of the 37 showed evidence at some time of roundworms or remnants in the biliary system, either within the US appearance of the stones ('bundles' and 'pipes') or separately on US, surgery or duodenoscopy. Biliary strictures, which occur in OCH, were not seen in our patients.