Pbc vs psc vs igg4 related sclerosi g cholangitis
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"IgG4 related cholangitis" AND "primary sclerosing cholangitis" AND "primary biliary cholangitis"
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PBC vs PSC vs IgG4-Related Sclerosing Cholangitis
Overview / Quick Comparison
| Feature | PBC | PSC | IgG4-SC |
|---|---|---|---|
| Full name | Primary biliary cholangitis | Primary sclerosing cholangitis | IgG4-related sclerosing cholangitis |
| Sex predominance | Female (9:1 F:M) | Male (2:1 M:F) | Male (strongly, >80%) |
| Age at presentation | 40–60 yrs | 25–45 yrs (median 36–39) | >60 yrs |
| Ducts involved | Small/medium intrahepatic only | Intra- and extrahepatic | Intra- and extrahepatic (mimics PSC) |
| Associated IBD | No | Yes (60–80%, usually UC) | No |
| Other organ involvement | Sicca syndrome, CREST, thyroiditis, celiac | None specific | Autoimmune pancreatitis, sialadenitis, retroperitoneal fibrosis |
| Cancer risk | Minimal (HCC only in cirrhosis) | Cholangiocarcinoma (10–15%) | Rare (CCA/cirrhosis uncommon) |
| Prognosis | Progressive → cirrhosis (now slowed by UDCA) | Variable; mean transplant-free survival ~12–20 yrs | Excellent with steroids |
Primary Biliary Cholangitis (PBC)
Pathogenesis
T lymphocyte–mediated destruction of small and medium intrahepatic bile ducts. Antimitochondrial antibodies (AMA) are present in 90–95% of patients — highly characteristic but their exact pathogenic role is unclear. Genome-wide studies implicate IL-12A and IL-12RB2 variants (IL-12 signaling pathway). Retained bile salts cause secondary hepatocellular injury.
Clinical Features
- Predominant symptoms: fatigue (50%) and pruritus (30%); ~50% asymptomatic at diagnosis
- Hypercholesterolemia, xanthelasmas, steatorrhea, metabolic bone disease (osteomalacia/osteoporosis)
- Extrahepatic autoimmunity: Sjögren syndrome, systemic sclerosis/CREST, thyroiditis, Raynaud phenomenon, celiac disease, rheumatoid arthritis
Diagnosis
- ↑ Alkaline phosphatase + ↑ GGT (first clue)
- AMA (anti-M2): sensitivity and specificity >95% at titer >1:40
- ↑ IgM (characteristic)
- Bilirubin often normal until late disease
- Liver biopsy: "florid duct lesion" — lymphoplasmacytic inflammation ± granulomas destroying interlobular ducts; portal-portal septal fibrosis
Treatment
- Ursodeoxycholic acid (UDCA) 13–15 mg/kg/day — dramatically improves outcomes and slows progression
- Obeticholic acid (farnesoid X receptor agonist) — approved for inadequate response to UDCA
- Pruritus: cholestyramine, rifampicin, naltrexone, ondansetron
- Liver transplantation for advanced disease (can recur in allograft)
Primary Sclerosing Cholangitis (PSC)
Pathogenesis
Immune-mediated injury to both intrahepatic and extrahepatic bile ducts. Key features:
- T-cell and autoantibody-mediated periductal inflammation
- Association with HLA-B8, HLA-A01, B08, DRB1*03
- "Gut-liver axis" hypothesis: T cells activated in damaged UC mucosa migrate to liver, cross-react with bile duct antigens
- Microbiome and toxic bile theories also implicated
Clinical Features
- Often asymptomatic at presentation — identified by ↑ ALP
- When symptomatic: fatigue, pruritus, upper abdominal pain, fever (cholangitis)
- ~60–80% have concurrent IBD (typically pan-UC with rectal sparing and ileitis — a "PSC-IBD" phenotype distinct from classic UC)
- Cholangiocarcinoma (10–15% lifetime risk) — major cause of death
- Also increased risk of colorectal cancer (in PSC-IBD)
Subtypes
- Large-duct PSC (classic): cholangiographic disease — intrahepatic ± extrahepatic ducts
- Small-duct PSC (5–20%): clinical/biochemical/histologic PSC without cholangiographic findings; better prognosis, no CCA risk
- PSC-AIH overlap (~7.5%): more responsive to immunosuppression, more common in children
Diagnosis
- ↑ ALP (90% of patients), ± ↑ AST/ALT
- pANCA positive in ~80% (non-specific; also positive in UC)
- ANA/ASMA in 25%; AMA is negative (if positive → think PBC)
- MRCP (gold standard imaging): "beaded" appearance — multifocal short strictures with intervening dilation
- Liver biopsy: "onion-skin" periductal fibrosis around atrophic ducts → eventual obliteration leaving "tombstone" scar → biliary cirrhosis
Treatment
- No proven effective pharmacologic therapy (UDCA has not shown mortality benefit in PSC)
- Endoscopic biliary dilatation/stenting for dominant strictures
- Surveillance: annual CA 19-9 + MRCP for cholangiocarcinoma; colonoscopy q1–2 years for colorectal cancer
- Liver transplantation is definitive treatment; PSC can recur post-transplant (~25%)
- Children: more responsive to medical therapy; high overlap with AIH
IgG4-Related Sclerosing Cholangitis (IgG4-SC)
Pathogenesis
A biliary phenotype of IgG4-related disease (IgG4-RD). Characterized histologically by:
- Dense lymphoplasmacytic infiltrate of IgG4+ plasma cells and eosinophils
- Obliterative phlebitis
- Storiform (whorled) fibrosis
Mechanism: antigen-driven immune response (possibly environmental — solvents, industrial gases) → B cells produce IgG4 → activated T cells secrete profibrotic cytokines (TGF-β, IL-10, IL-4, IL-13 — Th2 profile). RANKL from plasma cells activates myeloid-derived suppressor cells → suppress T-cell proliferation → induce Th2 differentiation.
Clinical Features
- Men >60 years — most distinctive demographic
- Often presents as obstructive jaundice ± pruritus
- Frequent concurrent autoimmune pancreatitis (type 1 AIP) — look for "sausage pancreas" on CT, "capsule sign"
- Other organ involvement: salivary gland swelling (sialadenitis/Mikulicz disease), retroperitoneal fibrosis, aortitis, tubulointerstitial nephritis
- No IBD association
Diagnosis — HISORt Criteria (Mayo Clinic)
- Histology: >10–20 IgG4+ plasma cells/HPF; obliterative phlebitis, storiform fibrosis
- Imaging: pancreatic/biliary ductal strictures; biliary stricture pattern mimicking PSC or CCA
- Serology: serum IgG4 elevated (in ~70% of cases; up to 30% are seronegative)
- IgG4 > 4× ULN is 100% specific for IgG4-SC (PSC patients may have mild IgG4 elevation but rarely exceed 2× ULN)
- Note: ~10% of PSC patients have elevated IgG4 (linked to specific HLA alleles)
- Other organ involvement
- Response to glucocorticoid therapy
IgG4-SC can be diagnosed if >20 IgG4+ plasma cells/HPF are seen on major papilla or bile duct pinch biopsy.
Cholangiographic Appearance
Can be identical to PSC (intrahepatic strictures) or mimic cholangiocarcinoma (dominant stricture) — this is the most clinically dangerous pitfall.
Treatment
- Glucocorticoids: >95% respond (prednisone 40 mg/day × 4 weeks → taper)
- Relapse frequent (31% of type 1 AIP/IgG4-SC) → maintenance with azathioprine or other immunosuppressants
- Refractory/relapsing disease: rituximab (B-cell depletion)
- Cirrhosis and cholangiocarcinoma are rare — long-term prognosis is excellent
Key Diagnostic Discriminators
| Clue | Think |
|---|---|
| Middle-aged woman + pruritus + ↑ ALP + positive AMA | PBC |
| Young/middle-aged man + UC + ↑ ALP + beading on MRCP | PSC |
| Older man + obstructive jaundice + no IBD + ↑ IgG4 + pancreatic enlargement + steroid-responsive | IgG4-SC |
| Positive pANCA | PSC (also UC, AIH) |
| ↑ IgM | PBC |
| Florid duct lesion + granulomas on biopsy | PBC |
| Onion-skin periductal fibrosis on biopsy | PSC |
| Obliterative phlebitis + storiform fibrosis on biopsy | IgG4-SC |
| IgG4 >4× ULN | IgG4-SC (100% specific) |
| AMA positive in suspected PSC | Exclude PBC overlap |
Treatment Summary
| Condition | First-line | Second-line | Definitive |
|---|---|---|---|
| PBC | UDCA 13–15 mg/kg/day | Obeticholic acid; fibrates | Liver transplant |
| PSC | No proven disease-modifying therapy | Endoscopic dilatation of dominant strictures | Liver transplant |
| IgG4-SC | Prednisone 40 mg/day | Azathioprine; rituximab | Usually not needed |
Sources: Robbins & Kumar Basic Pathology; Sleisenger and Fordtran's GI & Liver Disease; Goldman-Cecil Medicine; Harrison's Principles of Internal Medicine 22e
Autoimmune hepatitis
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