Lung Abscess

Key Features

Essentials of Diagnosis

• High fever, malaise, and weight loss in the setting of pneumonia

• Chest radiographs and CT scans usually reveal lung cavities, often with air-fluid levels

General Considerations

• Characterized by thick-walled cavities that form from inflammation and central necrosis following an initial pulmonary infection

• Occurs in a previously well child or one prone to aspiration; may be caused by

  • Staphylococcus aureus and other staphylococci

  • Streptococcus pneumoniae and streptococci

• May be seen in children with immunosuppression or underlying lung or systemic disease; may be caused by

  • Anaerobic and gram-negative organisms

  • Nocardia

  • Mycobacteria

  • Legionella species

  • Fungi (Candida and Aspergillus)

• May also occur via embolic spread

Clinical Findings

Symptoms and Signs

• High fever

• Malaise

• Weight loss

• In infants, evidence of respiratory distress can be present

Differential Diagnosis

• Loculated pyopneumothorax

• Neoplasms

• Plasma cell granuloma

• Infected congenital cysts and sequestrations

• Pneumatoceles, non–fluid-filled cysts, are common in children with empyema and usually resolve over time

Diagnosis

Laboratory Findings

• Elevated peripheral white blood cell count with a neutrophil predominance

• Elevated erythrocyte sedimentation rate or C-reactive protein

• Blood cultures are rarely positive except in the immunocompromised patient

• Sputum stains and cultures may confirm the diagnosis

Imaging

• Chest radiographs usually reveal single or multiple thick-walled lung cavities. Air-fluid levels can be present. Local compressive atelectasis, pleural thickening, or adenopathy may also occur.

• Chest CT scan may provide better localization and understanding of the lesions.

Diagnostic Procedure

• Direct percutaneous aspiration of material for stains and cultures guided by fluoroscopy or ultrasonography or CT imaging should be considered in the severely compromised or ill

Treatment

• Broad-spectrum intravenous antibiotics for uncomplicated abscesses in immunocompetent patients

• Additional coverage for anaerobic gram-negative organisms and fungi should be provided for others

• Prolonged therapy with 2–3 weeks of intravenous antibiotics followed by oral therapy may be required

• Attempts to drain abscesses via bronchoscopy have caused life-threatening airway compromise

• Surgical drainage or lobectomy is occasionally required, primarily in immunocompromised patients

Outcome

Complications

• Rare

• However, mediastinal shift, tension pneumothorax, and spontaneous rupture can occur

• Diagnostic maneuvers such as radiology-guided lung puncture to drain and culture the abscess may also cause a pneumothorax or a bronchopulmonary fistula.

Prognosis

• Radiographic resolution may be very slow (6 weeks–5 years); otherwise recovery occurs in most patients without long-term sequelae

• In the immunocompromised or medically complex patient, outlook depends on the underlying disorder

References