Intrahepatic Cholangiocarcinoma in Small-Duct Primary Sclerosing Cholangitis Associated With Crohn Disease: First Reported Case and Surveillance Implications.

Small-duct primary sclerosing cholangitis (sd-PSC) is traditionally regarded as a milder variant of PSC with a lower risk of hepatobiliary malignancy. Its association with intrahepatic cholangiocarcinoma (iCCA) remains unexplored. A 61-year-old woman with newly diagnosed Crohn disease presented with weight loss, anemia, and a liver mass initially suspected as hepatocellular carcinoma; biopsy confirmed poorly differentiated iCCA (CK7+/CK19+/Arginase-). MRCP showed normal large ducts with focal intrahepatic dilatation; liver biopsy demonstrated periductal onion-skin fibrosis diagnostic of sd-PSC. This report documents the first instance of metastatic iCCA in sd-PSC-CD, challenging current hepato-biliary malignancy surveillance paradigms in patients with inflammatory bowel disease.