Cholangitis in patients with ulcerative colitis (UC) can lead to misdiagnosis of primary sclerosing cholangitis (PSC). Furthermore, it can mimic cholangiocellular carcinoma, which also can lead to inappropriate and potentially harmful treatment of the patient. An 18-year-old male patient with known UC presented with pain in his right upper abdomen and elevation of the cholestatic liver enzymes (alkaline phosphatase: 197 U/L, γ-glutamyltransferase: 229 U/L) and increased inflammatory parameters (leukocytosis and CrP of 13.6 mg/L). Magnetic resonance cholangiopancreatography revealed unclear stenosis in the bifurcation of the main hepatic bile duct as well as in the prepapillary bile duct. Ultrasound (US) examination and endoscopic retrograde cholangiopancreatography showed dilatation of the intra -and extrahepatic bile ducts, which raised the suspicion of PSC. US image with dilated intra- and extrahepatic dilatation of the bile duct was also suggestive for autoimmune cholangitis. However, serum analysis revealed an elevated soluble interleukin-II receptor (1,305 U/mL), while immunoglobulin G4 was within normal ranges. Liver biopsy demonstrated hepatic inflammation and presence of granulomatous cells within the portal fields - convenient to sarcoidosis. After starting treatment with steroids, we observed a rapid clinical response with improvement of the dilated bile ducts and decrease of the initially elevated cholestatic liver enzymes. Sarcoidosis within the bile duct is a rare condition. Steroids are the treatment of choice and - along with the histology - are furthermore helpful to differentiate between several potential differential diagnoses like IgG4 cholangitis, primary biliary cholangitis, or PSC.