Case of IgG4-related sclerosing cholangitis with a normal serum IgG4 level: report of a case.

Although hilar cholangioma is the most common cause of stricture of the hilar bile duct, several diseases can contribute to stenosis. Here, we report on a patient with immunoglobulin (Ig) G4-related sclerosing cholangitis (IgG4-SC) of the hilar bile duct arising from obstructive jaundice. The patient had undergone laparoscopic cholecystectomy for the removal of gallstones. The differential diagnosis for icterus included hilar cholangiocarcinoma, primary sclerosing cholangitis, IgG4 sclerosing cholangitis, ischemic bile duct stenosis, a complication of cholecystitis, amputation neuroma, and iatrogenic stenosis. Numerous examinations were performed, but a definite diagnosis remained elusive. Because cholangiocarcinoma could not be ruled out, we proposed surgical resection. The patient subsequently underwent extended right liver lobectomy and intrahepatic cholangiojejunostomy. Pathological examination revealed numerous inflammatory cell infiltrates resembling IgG4-positive antibody plasma cells in the stromal layer of the stenotic bile duct walls. Hypertrophy of the nerve fiber fascicles was not observed. The serum IgG4 level of the patient was within the normal range. Few reports of IgG4-SC with a normal serum IgG4 level have been published. When this condition presents as it did in the present case, establishing a definite diagnosis can be difficult.