[Acute cholecystitis associated with IgG4-related sclerosing cholangitis: a case report].

A 72-year-old male patient with jaundice and hilar bile duct stenosis, initially suspected to have cholangiocarcinoma, was referred to our hospital. Subsequent cholangiography revealed bile duct stenosis improvement, and intraductal ultrasonography demonstrated homogeneous bile duct wall thickening. The increased serum immunoglobulin G4 (IgG4) levels and the presence of other organ lesions possibly indicated to IgG4-related sclerosing cholangitis (IgG4-SC). After 2 months, the patient developed acute cholecystitis. Endoscopic ultrasonography revealed circumferential wall thickening that extended from the common bile duct to the cystic duct. Cholangiography demonstrated cholecystic duct stenosis. The cholecystitis might have originated from bile stasis caused by cystic duct stenosis associated with IgG4-SC. Consequently, both IgG4-SC and the cholecystitis improved with steroid treatment.