[A case of spontaneous biloma accompanied with incarcerated choledocholithiasis]

A 55-year-old man was admitted with abdominal pain and nausea. CT-scan and US showed no abnormal findings. On the 5th hospital day, a large mass was palpable on the upper abdomen, and CT-scan (7th hospital day) demonstrated a large, cystic mass below the left lobe. A thoracentesis under ultrasound guidance obtained bile-stained fluid. PTCD revealed choledocholithiasis and severe dilatation of the common bile duct and the left branch. After conservative treatment, cholecystectomy and choledocholithotomy were performed. Biloma occurred mainly traumatically or iatrogenically. This case had a spontaneous biloma, and only 11 cases have been previously reported as spontaneous biloma in Japan.