Primary Sclerosing Cholangitis

Primary Sclerosing Cholangitis (PSC): Comprehensive Lecture Summary

Presenter: Prof. Jawad Ahmad, MD, FRCP, FAASLD

Source: CME Medical Lecture

1. Main Clinical Topics Discussed

• Definition, epidemiology, and etiology of PSC
• Diagnosis and differential diagnosis (including mimics)
• Disease monitoring and prognostication
• Malignancy risk (cholangiocarcinoma)
• Case-based illustrations of clinical presentations
• Review of current AASLD and EASL guidelines (both published within the prior year)

2. Key Learning Points, Guidelines, and Recommendations

Definition & Pathophysiology

• PSC is a chronic, progressive, destructive biliary disease of unknown cause
• Characterized by fibrosing and inflammatory strictures of both intra- and extrahepatic bile ducts
• Classic histological finding: "onion skin" periductal fibrosis
• Not a classic autoimmune disease — does not respond to immunosuppressive therapy
• Proposed mechanisms include:

- HLA and non-HLA immune associations (cellular and humoral dysfunction)

- pANCA positivity (~80%)

- Bile acid toxicity (effects on bile acid receptors, e.g., FXR/TGR5)

- Gut microbiome dysregulation

Diagnosis

• MRCP is the preferred diagnostic modality (high sensitivity and specificity; comparable to ERCP on imaging)
• ERCP should NOT be used as a primary diagnostic tool (both AASLD and EASL guidance)
• Liver biopsy is reserved for suspected small-duct PSC (normal cholangiogram with cholestatic enzymes)
• IgG4 level should be checked in all patients to exclude IgG4-related sclerosing cholangitis (especially in predominantly extrahepatic or pancreatic involvement)

- Note: serum IgG4 has limited reliability; a negative result does not exclude IgG4 disease

• Overlap syndromes (PSC + AIH, PSC + PBC) must be considered when ALT is significantly elevated, as AIH is treatable

Important Differential Diagnoses (PSC Mimics)

• Prior biliary surgery or trauma
• Recurrent pyogenic cholangitis / stone disease
• Ischemic cholangiopathy (e.g., hepatic artery injury, post-transplant)
• Intra-arterial chemotherapy–induced cholangiopathy
• HIV/AIDS cholangiopathy
• Drug-induced cholangiopathy (e.g., ketamine)
• COVID-19–associated cholangiopathy
• IgG4-related sclerosing cholangitis

Monitoring

• Risk stratification at diagnosis and at intervals thereafter (AASLD and EASL)
• Stable patients: clinical review and labs twice yearly
• Annual MRI/MRCP recommended (driven largely by cholangiocarcinoma surveillance)
• Non-invasive fibrosis markers (e.g., elastography) may be used; liver biopsy not routinely required
• CA 19-9: acknowledged as an imperfect but useful adjunctive test for cholangiocarcinoma surveillance
• High-risk features: symptomatic disease, markedly abnormal labs, advanced fibrosis on non-invasive testing, significant MRI changes

3. Specific Clinical Data, Statistics, and Study Results