PA24.3 | Viral & Toxic Hepatitis — Summary & Reflection

REFLECT

You have now mapped out the full landscape of hepatitis — from the five hepatotropic viruses to the drug metabolite that kills zone-3 hepatocytes in a precise, dose-dependent way.

Pause here and draw from memory a simple flowchart:

Acute hepatitis → [list 4–5 possible outcomes] → [for each outcome, name one histological correlate]

Then ask yourself: A patient presents with acute jaundice. What are the three most important questions in your history that would point you toward viral vs drug-induced vs autoimmune cause — before you order a single test?

Discuss your answers with a colleague or record them in your logbook. The ability to construct a differential at the history stage — before results — is the mark of a clinician, not just a student.

KEY TAKEAWAYS

Core take-aways from this module:

1. A & E = faeco-oral, self-limited. B, C, D = blood-borne, can be chronic. D is defective (requires HBV). E is dangerous in pregnancy (15–25% fulminant mortality).

1. HBV injury is immune-mediated (CD8⁺ CTL-driven), not direct cytopathic. Weak immune response → chronicity. Massive immune response → fulminant failure.

1. Acute hepatitis morphology: ballooning degeneration + Councilman (apoptotic) bodies + spotty necrosis + lobular disarray + Kupffer hyperplasia.

1. Chronic hepatitis: interface hepatitis (piecemeal necrosis) is the activity marker; fibrosis stage 0–4 guides prognosis. Ground-glass hepatocytes = chronic HBV only.

1. HBV carriers can develop HCC without cirrhosis via genomic integration — mandate 6-monthly surveillance.

1. Paracetamol toxicity: CYP2E1 → NAPQI → GSH depletion → centrilobular (zone 3) necrosis. NAC replenishes GSH. CCl₄ works similarly.

1. Idiosyncratic DILI is unpredictable; immune subtype shows eosinophilia. Drug withdrawal is the critical first step.

1. Distinguish by: viral serology (B/C/D), anti-HAV/HEV IgM, drug history, autoantibodies (ANA, anti-SMA, IgG), biopsy pattern.

1. Fulminant hepatic failure: panacinar necrosis, encephalopathy + coagulopathy; King's College Criteria guide transplant listing.