[A Case of Primary Sclerosing Cholangitis Difficult to Distinguish from a Hilar Cholangiocarcinoma]

A 78-year-old man, who had presented with onset of ulcerative colitis at the age of 56 years and had been in remission for the past several years, attended our hospital with a diagnosis of obstructive jaundice. A hilar cholangiocarcinoma with right hepatic artery invasion was suspected on contrast enhanced CT. An endoscopic retrograde cholangiography indicated Bismuth type 2 stenosis. The stenotic bile duct brushings revealed no malignancy. Primary sclerosing cholangitis(PSC)and IgG4- related cholangitis were included in the differential diagnosis; however, a significant result could not be obtained in any other examinations. A hilar cholangiocarcinoma could not be ruled out, and rt. hepatic lobectomy and caudate lobectomy with resection of the extrahepatic bile duct were performed after obtaining informed consent. The histopathological findings revealed no atypical cells in the stenotic lesion, but fibrosis and inflammatory cell infiltration were observed around the bile duct. These findings were consistent with PSC. On the other hand, atypical cell proliferation with lymph duct infiltration was found in the mucosa of the gall bladder. It is difficult to preoperatively diagnose PSC localized to the hilar bile duct, and if possible, the existence of concomitant malignant lesions in the biliary tract should be considered.