Autoimmune hepatitis (AIH), primary biliary cholangitis (PBC), and primary sclerosing cholangitis (PSC) are distinct chronic liver diseases with different etiologies, clinical features, diagnostics, and treatments. Below is a concise comparison:

1. Autoimmune Hepatitis (AIH)

• Definition: An autoimmune liver disease characterized by immune-mediated destruction of hepatocytes.
• Etiology: Unknown trigger; genetic predisposition (HLA-DR3, DR4); more common in women.
• Clinical Features:
  • Fatigue, jaundice, abdominal pain.
  • Can present acutely or chronically; may progress to cirrhosis.
  • Associated with other autoimmune diseases (e.g., thyroiditis, rheumatoid arthritis).
• Diagnostics:
  • Elevated liver enzymes (ALT, AST > ALP).
  • Positive autoantibodies: ANA, SMA, anti-LKM1.
  • Elevated IgG levels.
  • Liver biopsy: Interface hepatitis, lymphoplasmacytic infiltrates.
• Treatment:
  • Immunosuppression: Corticosteroids (prednisone) ± azathioprine.
  • Maintenance therapy to prevent relapse.
• Prognosis: Good with treatment; untreated can lead to cirrhosis or liver failure.

2. Primary Biliary Cholangitis (PBC)

• Definition: A chronic cholestatic disease due to immune-mediated destruction of small intrahepatic bile ducts.
• Etiology: Autoimmune; strongly associated with antimitochondrial antibodies (AMA); predominantly affects middle-aged women.
• Clinical Features:
  • Fatigue, pruritus (itching), jaundice (late).
  • Sicca syndrome, hyperlipidemia, osteoporosis.
  • Associated with autoimmune diseases (e.g., Sjögren’s, scleroderma).
• Diagnostics:
  • Elevated ALP, GGT; mild bilirubin increase (late).
  • AMA positive in 95% of cases; ANA may be present.
  • Liver biopsy (if needed): Nonsuppurative cholangitis, granulomas.
• Treatment:
  • Ursodeoxycholic acid (UDCA): Improves liver biochemistries, delays progression.
  • Obeticholic acid for UDCA non-responders.
  • Symptomatic treatment for pruritus (cholestyramine).
• Prognosis: Slowly progressive; can lead to cirrhosis. Liver transplant for end-stage disease.

3. Primary Sclerosing Cholangitis (PSC)

• Definition: A chronic cholestatic disease with inflammation and fibrosis of intra- and extrahepatic bile ducts, leading to strictures.
• Etiology: Unknown; likely immune-mediated; strong association with inflammatory bowel disease (IBD, especially ulcerative colitis); more common in men.
• Clinical Features:
  • Fatigue, pruritus, jaundice, recurrent cholangitis.
  • May be asymptomatic initially, detected via abnormal LFTs.
  • Increased risk of cholangiocarcinoma (10-15%).
• Diagnostics:
  • Elevated ALP, GGT; bilirubin may rise with progression.
  • MRCP/ERCP: “Beaded” bile ducts (strictures and dilatations).
  • Autoantibodies: p-ANCA positive in 70%; AMA negative.
  • Liver biopsy (if needed): Periductal fibrosis (“onion-skinning”).
• Treatment:
  • No specific therapy; UDCA may improve LFTs but no survival benefit.
  • Manage complications (e.g., stents for strictures, antibiotics for cholangitis).
  • Liver transplant for end-stage disease or cholangiocarcinoma.
• Prognosis: Progressive; median transplant-free survival ~10-20 years.

Key Differences

Feature	AIH	PBC	PSC
Target	Hepatocytes	Small bile ducts	Large intra/extrahepatic bile ducts
Demographics	Women > Men, any age	Middle-aged women	Men > Women, younger (30-40)
Autoantibodies	ANA, SMA, LKM1	AMA (95%)	p-ANCA (70%)
Liver Enzymes	AST/ALT ↑↑	ALP/GGT ↑↑	ALP/GGT ↑↑
Imaging	Normal	Normal	Beaded ducts (MRCP/ERCP)
Associations	Autoimmune diseases	Sjögren’s, thyroiditis	IBD (70-80%)
Cancer Risk	Hepatocellular carcinoma (HCC)	HCC (late)	Cholangiocarcinoma
Treatment	Immunosuppression	UDCA, obeticholic acid	Supportive, transplant

Summary

• AIH is a hepatocellular autoimmune disease treated with immunosuppression.
• PBC affects small bile ducts, is AMA-positive, and responds to UDCA.
• PSC involves large bile ducts, is linked to IBD, and has no definitive therapy but a high cholangiocarcinoma risk.

For precise diagnosis, a combination of serology, imaging, and sometimes biopsy is required. Treatment focuses on slowing progression and managing complications, with liver transplantation as an option for end-stage disease in all three.