Huge solitary-infected liver cyst successfully managed by deroofing operation to remove 3.8 l of pus.

Simple liver cysts are usually asymptomatic, and complications are uncommon. However, infection of cysts can very occasionally occur, and this troublesome complication requires treatment. An 87-year-old woman admitted for dyspnea, abdominal discomfort, fever, and mild icterus underwent ultrasonographic (US) and computed tomography (CT) examinations, and a huge cystic lesion was identified in the right hepatic lobe. The diagnosis of an infected gigantic liver cyst was made by abdominal CT and percutaneous transhepatic drainage under ultrasonographic guidance. The pus viscosity was so high that pus drainage was ineffective. Bacterial culture was positive for Klebsiella pneumoniae. The cyst diameter was approximately 21 cm, and the total pus discharge was 3.8 l. Emergency operation to fenestrate the cyst wall relieved the patient's critical condition. This report is clinically significant because 3.8 l of pus may be one of the largest reported quantity of drained pus from an infected cyst. We found no reports of > 3.8 l of drained pus in an English literature search. It is also very rare that imaging identified postoperative liver regeneration filling the huge empty space previously occupied by the cyst. Large liver cysts in older people should be carefully followed, preparing for the rare possibility of infection.