Primary sclerosing cholangitis (PSC) is a chronic, progressive, idiopathic inflammatory fibrosis of the intrahepatic and extrahepatic bile ducts. Concentric ('onion-skin') fibrosis develops in the bile duct wall, leading to multifocal strictures. Normal or dilated segments between strictures create the characteristic beaded appearance. PSC shows a strong association with inflammatory bowel disease (particularly ulcerative colitis); IBD is present in 70-80% of patients. It is an important risk factor for cholangiocarcinoma development (10-15% lifetime risk). Mean age at diagnosis is 40 years, with a 2:1 male predominance.
Age Range
20-60
Peak Age
40
Gender
Male predominant
Prevalence
Uncommon
In PSC, T-lymphocyte infiltration and periductal fibrosis develop around the bile duct epithelium. Immune-mediated damage causes concentric collagen deposition (onion-skin pattern) in the duct wall, leading to luminal narrowing (strictures). Normal or mildly dilated segments between strictures create the characteristic beaded appearance on MRCP. Chronic bile stasis and recurrent cholangitis episodes progress to hepatic fibrosis and subsequently biliary cirrhosis. Periductal fibrosis appears as T2-hypointense periductal thickening on MRI because fibrous tissue has short T2 relaxation time due to low water content. Cancer risk is increased at dominant stricture sites; surveillance is performed with MRCP and CA 19-9.
Alternating narrowing-dilatation pattern of bile ducts on MRCP with multifocal short-segment strictures and intervening normal/dilated segments — resembling a string of beads. Considered pathognomonic for PSC.
Multifocal short-segment strictures of intrahepatic and extrahepatic bile ducts with intervening normal or mildly dilated segments on MRCP — beaded appearance. Strictures typically show diffuse and bilateral involvement. Intrahepatic involvement is more common, and peripheral duct pruning may be present.
Report Sentence
Multifocal short-segment strictures with intervening dilated segments of intrahepatic bile ducts on MRCP demonstrate beaded appearance consistent with primary sclerosing cholangitis.
Concentric, smooth T2-hypointense periductal thickening around bile ducts on T2-weighted images. This finding is the imaging correlate of 'onion-skin fibrosis.' Thickening is particularly prominent around hilar and extrahepatic ducts.
Report Sentence
T2-hypointense concentric periductal thickening around bile ducts is consistent with periductal fibrosis due to primary sclerosing cholangitis.
Late-phase periductal contrast enhancement around bile ducts on contrast-enhanced MRI. Enhancement is more prominent during active inflammation. Disproportionate wall thickening and intense enhancement at dominant stricture site raises concern for superimposed cholangiocarcinoma.
Report Sentence
Late-phase periductal contrast enhancement around bile ducts is consistent with active inflammatory process in primary sclerosing cholangitis.
Diffuse bile duct wall thickening and enhancement on contrast-enhanced CT. Low-density periportal halo along intrahepatic periportal areas and peripheral duct pruning may be present. Extrahepatic duct wall thickening may also be seen.
Report Sentence
Diffuse wall thickening and enhancement of intra- and extrahepatic bile ducts consistent with primary sclerosing cholangitis.
Bile duct wall thickening and irregularity of intra- and extrahepatic ducts on B-mode US. Segmental dilatation and narrowing may be visible. Gallbladder wall thickening and polyps frequently accompany PSC. In advanced stages, hepatic fibrosis/cirrhosis findings (heterogeneous parenchyma, lobulated contour, splenomegaly) may be present.
Report Sentence
Bile duct wall thickening, irregularity, and segmental dilatation areas are present, findings potentially consistent with PSC; further evaluation with MRCP is recommended.
Diffusion restriction (DWI hyperintense, low ADC) at a dominant stricture raises suspicion for superimposed cholangiocarcinoma. In PSC, a dominant stricture is defined as narrowing exceeding 1 cm or complete duct obstruction. DWI may help differentiate benign stricture from malignant transformation.
Report Sentence
Diffusion restriction at the dominant stricture site raises concern for cholangiocarcinoma developing on PSC background; further evaluation (brush cytology, CA 19-9) is recommended.
Hepatic morphological changes in advanced PSC: lobar atrophy-hypertrophy complex (typically left lateral and caudate lobe hypertrophy), lobulated contour, periportal low density. Splenomegaly, portal hypertension signs, and loss of peripheral intrahepatic ducts (pruning) may accompany.
Report Sentence
Lobar atrophy-hypertrophy complex, lobulated hepatic contour, and peripheral intrahepatic duct pruning are consistent with advanced primary sclerosing cholangitis.
Criteria
Involvement of intrahepatic and/or extrahepatic large bile ducts; typical stricture pattern on MRCP/ERCP. Comprises the vast majority of patients (90%).
Distinct Features
Beaded appearance on MRCP is prominent. May present as intrahepatic alone (25%), extrahepatic alone (5%), or combined involvement (70%). ALP significantly elevated.
Criteria
Normal MRCP/ERCP findings with histological changes consistent with PSC on liver biopsy (periductal fibrosis, onion-skin lesion). Approximately 5-10% of patients.
Distinct Features
No large duct involvement on imaging; diagnosis requires biopsy. Better prognosis than large duct PSC; cholangiocarcinoma risk is low. 12-23% may progress to large duct PSC over time.
Criteria
Cholangiographic findings of PSC plus laboratory (elevated IgG, ANA/SMA positivity) and histology (interface hepatitis) consistent with autoimmune hepatitis. Particularly common in children.
Distinct Features
Both cholangitis and hepatitis components present. Responds to immunosuppressive therapy (corticosteroids + azathioprine). Transaminases significantly higher than other PSC forms.
Criteria
Narrowing to ≤1.5 mm in common bile duct or ≤1 mm in hepatic duct diameter. Present in 36-50% of patients. High-risk subgroup for cholangiocarcinoma development.
Distinct Features
Main cause of jaundice, pruritus, and cholangitis attacks. Treated with endoscopic dilatation and stenting. Asymmetric wall thickening on MRCP, DWI restriction, and CA 19-9 >129 U/mL are alarm signs for cholangiocarcinoma.
Distinguishing Feature
Recurrent pyogenic cholangitis shows prominent intraductal stones and pigment debris; strictures tend to be segmental and unilateral. PSC shows diffuse bilateral strictures with rare intraductal stones.
Distinguishing Feature
Benign biliary stricture is typically solitary and focal (post-surgical/traumatic); PSC strictures are multifocal and diffuse.
Distinguishing Feature
Cholangiocarcinoma shows focal mass with segmental duct dilatation; PSC shows diffuse multifocal stricture pattern. However, cholangiocarcinoma can develop on PSC background — asymmetric thickening and DWI restriction at dominant stricture is alarming.
Distinguishing Feature
Acute cholangitis presents acutely with Charcot triad and is usually due to single-level obstruction. PSC shows chronic course with multifocal stricture pattern.
Urgency
routineManagement
medicalBiopsy
Not NeededFollow-up
6-monthThere is no curative treatment for PSC; ursodeoxycholic acid (UDCA) is the most commonly used medication but its benefit is controversial. Dominant strictures are treated with endoscopic balloon dilatation. Liver transplantation is the only curative option in advanced disease. Cholangiocarcinoma surveillance (annual MRCP + CA 19-9) is vital. Concurrent IBD monitoring (colonoscopy) should be maintained. Median transplant-free survival is 12-18 years.
PSC is a progressive disease that can progress to cirrhosis, liver failure, and cholangiocarcinoma. Cholangiocarcinoma risk is 10-15%. Lifelong cholangiocarcinoma surveillance is required. PSC should be screened in IBD patients. Liver transplantation is the final treatment option.