A 35-year-old man from Mumbai with a 15-year history of hepatitis B (HBeAg positive, HBV DNA 8 × 10^5 copies/mL) presents with acute onset jaundice, right upper quadrant pain, and fever. Laboratory findings: total bilirubin 6.5 mg/dL, ALT 4200 IU/L, AST 3800 IU/L, albumin 3.2 g/dL, INR 1.3. Serological testing shows HBsAg positive, anti-HBc positive, HBeAg positive, anti-HBe negative, anti-HAV IgM negative, anti-HCV negative. Abdominal ultrasound shows hepatomegaly with normal portal vein flow. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Acute Exacerbation of Chronic Hepatitis B ### Distinguishing Acute Exacerbation from Superinfection **Key Point:** The absence of anti-HAV IgM and the presence of HBsAg + anti-HBc (markers of chronic HBV) confirm this is an acute exacerbation of pre-existing chronic hepatitis B, NOT a new superinfection. | Feature | Acute Exacerbation | HAV Superinfection | HEV Superinfection | |---------|-------------------|-------------------|--------------------| | HBsAg | Positive | Positive | Positive | | Anti-HBc | Positive (IgG) | Positive (IgG) | Positive (IgG) | | Anti-HAV IgM | Negative | **Positive** | Negative | | Anti-HEV IgM | Negative | Negative | **Positive** | | HBeAg | May be positive or negative | Positive (if HBeAg+ before) | Positive (if HBeAg+ before) | | Mechanism | Immune flare of existing HBV | New HAV infection on HBV | New HEV infection on HBV | **This patient:** Anti-HAV IgM **negative** → rules out HAV superinfection. ### Pathophysiology of Acute Exacerbation **High-Yield:** Acute exacerbations of chronic HBV occur due to: 1. Spontaneous immune flare (HBV-specific CD8+ T-cell activation) 2. Viral reactivation (e.g., after immunosuppression withdrawal) 3. Emergence of HBeAg-negative mutants 4. Superinfection with HDV (hepatitis D) This patient's **HBeAg-positive status with high HBV DNA** suggests active viral replication with an acute immune response. ### Clinical Features Supporting Exacerbation (NOT Fulminant Failure) **Clinical Pearl:** Although INR is mildly elevated (1.3), this patient does NOT meet criteria for fulminant hepatic failure: - INR 1.3 is only mildly elevated; fulminant failure requires INR > 1.5 - Albumin 3.2 g/dL is low-normal, not severely depleted - No mention of encephalopathy or asterixis - Normal portal vein flow on ultrasound (no portal hypertension/cirrhosis) These findings indicate **acute exacerbation with preserved hepatic reserve**, not fulminant failure. ### Serological Interpretation Algorithm ```mermaid flowchart TD A["HBsAg positive?"]:::decision A -->|Yes| B["Anti-HBc positive?"]:::decision A -->|No| Z["Not HBV"]:::outcome B -->|Yes| C["Chronic HBV"]:::outcome B -->|No| D["Acute HBV"]:::outcome C --> E["Anti-HAV IgM positive?"]:::decision E -->|Yes| F["HAV superinfection"]:::outcome E -->|No| G["Acute exacerbation of chronic HBV"]:::outcome D --> H["Check anti-HBc IgM"]:::action ``` ### Management Implications **Mnemonic: CARE** — Consider Antivirals, Rule out complications, Evaluate synthetic function, Exclude superinfections Acute exacerbations of chronic HBV are managed with: - Supportive care (most resolve spontaneously) - Antiviral therapy if INR > 1.5 or encephalopathy develops - Monitoring for fulminant progression - Screening for HDV superinfection (anti-HDV) [cite:Harrison 21e Ch 360; Robbins 10e Ch 18]