🩻 TOACS FCPS Station · X-ray Chest for Lung Abscess
📷 Chest X-ray – Pulmonary Abscess
🔍 Key radiographic features:
- ✓ Thick-walled cavity – irregular, >3 mm wall thickness
- ✓ Air-fluid level – characteristic of lung abscess
- ✓ Location – often dependent (lower lobes, posterior segments)
- ✓ Surrounding consolidation – ill-defined opacity
- ✓ Differential – pneumatocele (thin-walled, resolves spontaneously)
📋 Clinical scenario (examiner prompt)
A 5‑year‑old child is brought to the emergency department with a 3‑week history of fever, cough, and weight loss. The mother reports that the cough is productive of foul‑smelling sputum. On examination, the child has decreased breath sounds and dullness in the right lower chest. A chest X‑ray (see image) shows a thick‑walled cavitary lesion with an air‑fluid level in the right lower lobe. The child has a history of frequent dental caries and recent tooth extraction.
🧑⚕️ Examiner tasks · TOACS
1. Identify the diagnosis from the clinical image and context.
2. Describe the radiographic findings (thick-walled cavity, air-fluid level, location).
3. Explain the etiology and pathogenesis (aspiration of oral anaerobes, necrotizing pneumonia).
4. Discuss management (antibiotics, drainage, surgery).
🎯 Expected answers (for examiners)
- • Diagnosis: Pulmonary abscess (lung abscess)
- • Radiographic findings: Thick-walled cavitary lesion (wall thickness >3 mm) with an air-fluid level; often in dependent lung segments (lower lobes, posterior segments); surrounding consolidation
- • Pathophysiology: Necrotizing infection of lung parenchyma → cavity formation and pus accumulation; most common from aspiration of oral anaerobes (Fusobacterium, Peptostreptococcus, Prevotella). Other pathogens: S. aureus, S. pneumoniae, Streptococcus anginosus (milleri group)
- • Risk factors: Aspiration (poor oral hygiene, dental caries, tooth extraction, seizure disorder), immunodeficiency, CF, CGD, foreign body, trauma
- • Diagnosis: CXR, CT chest (better characterization), blood cultures, sputum culture (often contaminated)
- • Treatment: IV clindamycin or ampicillin-sulbactam for 2-3 weeks, then oral for total 3-4 weeks. CT-guided drainage for large abscess (>4-6 cm) or failure of antibiotics. Surgical lobectomy for failure of antibiotics + drainage, massive hemoptysis, bronchopleural fistula.
• Imaging: Thick-walled cavity with air-fluid level
• Most common pathogen: Oral anaerobes (aspiration)
• First-line antibiotics: Clindamycin or ampicillin-sulbactam
• Duration: 3-4 weeks total (IV 2-3 weeks, then oral)
• Drainage indication: Large >4-6 cm, failure of antibiotics
• Surgery indication: Failure of antibiotics + drainage, massive hemoptysis, bronchopleural fistula
⚡ Quick FCPS‑style MCQ
A child with fever, cough, and foul-smelling sputum has a chest X-ray showing a thick-walled cavity with an air-fluid level. The most likely diagnosis and first-line treatment are:
A. Pneumatocele – observation B. Pulmonary abscess – clindamycin or ampicillin-sulbactam C. Tuberculosis – quadruple therapy D. Empyema – chest tube drainage📌 Topic summary · Pulmonary Abscess (Chest X-ray)
Thick-walled cavity with air-fluid level
Aspiration of oral anaerobes
Clindamycin/ampicillin-sulbactam 3-4 weeks
Large >4-6 cm or failure of antibiotics
Massive hemoptysis, bronchopleural fistula
Better characterization, planning
| Feature | Pulmonary Abscess |
|---|---|
| Definition | Necrotizing infection of lung parenchyma with cavity formation and air-fluid level |
| Imaging – CXR | Thick-walled cavity (>3 mm) with air-fluid level; often lower lobes, dependent segments |
| Imaging – CT | Better characterization: thick-walled cavity, necrotizing pneumonia, size, loculation |
| Common pathogens | Oral anaerobes (Fusobacterium, Peptostreptococcus), S. aureus, S. pneumoniae, Streptococcus anginosus |
| First-line antibiotics | Clindamycin (30-40 mg/kg/day) or ampicillin-sulbactam (100-200 mg/kg/day) |
| Duration | 3-4 weeks total (IV 2-3 weeks, then oral) |
| Percutaneous drainage | Large abscess (>4-6 cm), failure of antibiotics after 7-10 days, critically ill |
| Surgery (lobectomy) | Failure of antibiotics + drainage, massive hemoptysis, bronchopleural fistula |