A Rare and Aggressive Klatskin Tumor Revealed by Magnetic Resonance Cholangiopancreatography (MRCP): A Diagnostic Case Report

A 57-year-old man with controlled hypertension and moderate daily alcohol and tobacco consumption presented with one week of progressive severe obstructive jaundice, intense pruritus, acholic stools, and dark urine. Total bilirubin on admission was 25.1 mg/dL, rising to 29.4 mg/dL within 48 hours despite supportive care. Initial endoscopic retrograde cholangiopancreatography (ERCP) completely failed due to the inability to cannulate the biliary tree. Tumor markers obtained after this failure revealed a strikingly elevated CA 19-9 of 4,872 U/mL and carcinoembryonic antigen (CEA) of 18.6 ng/mL. Magnetic resonance cholangiopancreatography (MRCP) demonstrated an infiltrative stricture at the hepatic duct confluence with abrupt ductal termination, separation of right and left hepatic ducts, a shouldering sign, and predominant right-lobe intrahepatic biliary dilatation - findings diagnostic of Bismuth-Corlette type IIIa Klatskin tumor. No vascular encasement or distant metastases were identified. A second ERCP successfully deployed an uncovered 10 × 80 mm self-expanding metal stent, leading to rapid clinical and biochemical improvement. The patient was promptly referred to a specialized hepatobiliary unit for evaluation of curative-intent resection. This case highlights how contemporary high-resolution MRCP combined with extreme CA 19-9 elevation can establish a confident noninvasive diagnosis of Klatskin tumor when initial ERCP fails, dramatically shortening diagnostic delay and accelerating the pathway to potentially curative surgery.