Paper II
Question
Lobar pneumonia
Answer
Lobar pneumonia is an acute bacterial infection (classically Streptococcus pneumoniae) that produces consolidation of an entire lobe or a large part of a lobe.
Stages (classic 4 stages over ~1 week):
- Congestion: Lung is heavy, red, boggy; vascular congestion with intra-alveolar fluid and few neutrophils; numerous bacteria present.
- Red hepatization: Lung becomes red, firm, and airless (liver-like); alveolar spaces packed with neutrophils, red cells, and fibrin.
- Grey hepatization: Lung remains firm but turns grey-brown as red cells disintegrate; fibrinosuppurative exudate persists within alveoli.
- Resolution: Exudate is enzymatically digested, resorbed, or organized; normal architecture is largely restored.
Complications:
- Lung abscess
- Empyema
- Pleuritis with pleural effusion
- Organization (carnification — conversion of exudate into fibrous tissue)
- Bacteraemia with metastatic infection (meningitis, endocarditis, arthritis)
- Respiratory failure in severe cases
Clinical features: High fever, productive cough (rusty sputum), pleuritic chest pain, dyspnoea; chest X-ray shows lobar/segmental consolidation with air bronchograms. Treated with appropriate antibiotics; most patients recover completely with resolution.