Cholangitis complicated by infection of a simple hepatic cyst

An 87-year-old man was admitted to our hospital due to fever and elevated liver enzymes. Computed tomography (CT) scan revealed bile duct stones with a dilated biliary system, which confirmed the diagnosis of cholangitis. A 12-cm simple hepatic cyst was also seen in the right liver, which had been detected on CT scan 5 years before, and did not change in size. Fever did not subside even after endoscopic biliary drainage and a repeated CT scan showed an enlarged cyst up to 14 cm, suggesting cyst infection. An enlarged hepatic cyst collapsed after percutaneous transhepatic drainage, along with resolution of fever. Simple hepatic cysts are common and most of them are asymptomatic. Infection of simple hepatic cysts is a rare condition and the major entry route is considered as the biliary tract as communication between the biliary tract and cysts is reportedly observed in those cases. However, in our case, no communication was seen on cholangiogram or cystogram on fluoroscopy and bilirubin level of the cyst aspirate was low. Given the fact that patients with cholangitis are rarely complicated by hepatic cyst infection, other routes of bacterial entry to simple hepatic cysts should also be considered.