Giant liver cyst caused by tuberculosis infection and masquerading as malignant peritonitis.

Liver involvement in tuberculosis infection is rare, and the radiological findings have previously been interpreted asmultiple liver tumors, hemangioma, abscess, or cirrhosis [1–3]. Conversely, hepatic cyst is a common benign liver tumor that is usually easy to diagnose as a simple hepatic cyst. Despite advances in imaging techniques, differentiating complicated hepatic cysts fromother tumors, including malignancies, sometimes remains challenging. We describe a rare case of a giant liver cyst caused by tuberculosis and masquerading asmalignant peritonitis. A 60-year-old man was referred to our hospital with a 3-week history of persistent postprandial nausea. Computed tomography showed a wall-enhanced cystic lesion in the left lobe of the liver, measuring 200mm in maximum diameter (●" Fig.1). Magnetic resonance imaging showed a multiloculated cyst with hyperintensity on T2-weighted imaging and decreased diffusion at the cystic wall on diffusion-weighted imaging (DWI) (●" Fig.2). On endoscopic ultrasonography, the cyst had multilocular septa (●" Fig.3). Because the patient remained symptomatic, and DWI suggested the possibility of malignancy, we decided that surgery should be performed. Laparotomy revealed many white nodules in the abdominal cavity, suggestingmalignant peritonitis (●" Fig.4). However, these nodules and the cystic wall included granFig.1 Computed tomography showed a wall-enhanced cystic lesion in the lobe of the liver, with a maximum diameter of 200mm.