Infected hepatic cyst in a patient with multiple hepatic cysts: report of a case diagnosed by change of ultrasonographic findings.

Liver cysts are commonly observed, but infection of a liver cyst is a rare complication. Although patients have clinical symptoms, such as a high-grade fever and abdominal pain, diagnosing an infected cyst by abdominal ultrasonography, computed tomography (CT) with contrast medium and magnetic resonance imagings (MRI) is not always easy. We experienced an unusual case who had only clinical symptoms, such as high-grade fever and a right quadrant abdominal pain, but no imaging findings when admitted. Careful observation using ultrasonography once a week revealed signs of an infected cyst containing echogenic fluid 32 days after admission. We performed percutaneous transhepatic cystic drainage. When a patient has liver cysts and complains of high-grade fever and abdominal pain, liver cysts should be considered as a focus of sepsis, and we recommend repeat use of ultrasonography or CT, even if no typical findings occur the first time.