148. Acute and chronic hepatitis - classification, etiology, pathogenesis, clinical manifestations.

Acute and chronic hepatitis - classification, etiology, pathogenesis, and clinical manifestations.

Hepatitis

Hepatitis is inflammation of the liver parenchyma, which may be acute (sudden onset, <6 months) or chronic (persistent ≥6 months).

Classification

By duration

By etiology

Etiology

Acute hepatitis

• Viruses: HAV, HBV (especially with superinfection), HCV (rarely), HDV, HEV.
• Drugs and toxins: acetaminophen overdose, certain antibiotics, herbal products.
• Ischemia (shock liver).

Chronic hepatitis

• HBV, HCV, HDV(if chronic infection persists).
• Autoimmune hepatitis.
• Metabolic/genetic: Wilson’s disease, alpha-1 antitrypsin deficiency, hemochromatosis.
• Non-alcoholic fatty liver disease (NAFLD).

Pathogenesis

Acute hepatitis

1. Viral entry or toxin exposure → hepatocyte injury.
2. Direct cytopathic effects or immune-mediated cytotoxicity - the immune system attacks infected hepatocytes, causing further damage
3. Inflammatory cell infiltration (mainly lymphocytes) - Immune cells (mostly T lymphocytes ) enter liver tissue to fight infection. This leads to swelling and inflammation of the liver.
4. Hepatocyte necrosis and apoptosis → possible full recovery or progression to chronic damage

Chronic hepatitis

1. Persistent viral infection or ongoing autoimmune/metabolic injury.
2. Repeated cycles of hepatocyte necrosis and regeneration.
3. Progressive fibrosis → architectural distortion.
4. May advance to cirrhosis (severe fibrosis with nodules). and hepatocellular carcinoma.

Clinical manifestations

Acute hepatitis

• Often asymptomatic in mild cases.
• Prodromal (pre-icteric) phase:
• Fatigue, malaise.
• Anorexia, nausea, vomiting.
• Arthralgia (especially in HBV).
• Icteric phase:
• Jaundice.
• Dark urine (bilirubinuria), pale stools.
• Pruritus.
• Recovery phase:
• Gradual resolution of symptoms.

Chronic hepatitis

• Often insidious and asymptomatic initially.
• Fatigue, malaise.
• Mild right upper quadrant discomfort.
• Possible jaundice (in advanced cases).
• Signs of chronic liver disease (spider angiomas, palmar erythema, gynecomastia).
• Late complications: portal hypertension, ascites, variceal bleeding, hepatic encephalopathy, hepatocellular carcinoma.