Allergic Bronchopulmonary Aspergillosis (ABPA) 

1. Definition

Allergic Bronchopulmonary Aspergillosis (ABPA) is a hypersensitivity lung disease caused by an exaggerated immune response to colonization of airways by  Aspergillus fumigatus

It occurs almost exclusively in:

  • Asthma
  • Cystic fibrosis

2. Pathophysiology 

  • No tissue invasion → colonization only
  • Immune hyperreaction → Type I + Type III + Type IV hypersensitivity

3. Epidemiology

  • Asthma patients: ~1–2%
  • Cystic fibrosis: up to 10%
  • More common in:
    • Long-standing asthma
    • Poorly controlled disease

4. Clinical Features

  • Recurrent wheezing (asthma-like)
  • Productive cough
  • Brownish mucus plugs (classic)
  • Hemoptysis (occasionally)

Systemic Features

  • Fever (low-grade)
  • Malaise

Red Flags Suggesting ABPA

  • Asthma not responding to standard therapy
  • Recurrent “pneumonia” with fleeting infiltrates
  • Steroid-dependent asthma

5. Radiology

Chest X-ray-Transient (fleeting) pulmonary infiltrates

HRCT Chest 

  • Central bronchiectasis (pathognomonic)
  • Mucoid impaction
    • “Finger-in-glove” appearance
  • High-attenuation mucus (HAM) → highly specific
  • Tree-in-bud pattern (occasionally)

 

6. Diagnostic Criteria (ISHAM Criteria)

Essential Criteria

  1. Asthma or cystic fibrosis
  2. Elevated total IgE (>1000 IU/mL typically)

Plus ≥2 of the following

  • Aspergillus-specific IgE/IgG positive
  • Peripheral eosinophilia (>500 cells/µL)
  • Radiological findings (bronchiectasis, infiltrates)
  • Positive skin prick test to Aspergillus

7. Laboratory Findings

Parameter

Finding

Total IgE

↑↑ (>1000 IU/mL)

Specific IgE (Aspergillus)

Positive

IgG (precipitins)

Positive

Eosinophils

↑

Sputum

Hyphae + mucus plugs

8. Staging of ABPA 

Stage

Description

Stage I

Acute

Stage II

Remission

Stage III

Exacerbation

Stage IV

Steroid-dependent asthma

Stage V

Fibrotic lung disease

9. Differential Diagnosis

  • Severe asthma
  • Pulmonary tuberculosis (important in India)
  • Bronchiectasis (non-ABPA)
  • Chronic eosinophilic pneumonia
  • Hypersensitivity pneumonitis

10. Treatment 

A. First-Line: Systemic Corticosteroids -Prednisolone Regimen

  • 0.5 mg/kg/day for 2 weeks
  • Then alternate day for 6–8 weeks
  • Gradual taper over 3–6 months

Monitoring

  • Total IgE ↓ by 25–50% = response

B. Antifungal Therapy (Steroid-Sparing)

1. Itraconazole (First choice)

  • Dose: 200 mg BD
  • Duration: 16 weeks

2. Alternatives

  • Voriconazole
  • Posaconazole

C. Biologics (For Refractory ABPA)

1. Anti-IgE

  • Omalizumab

2. Anti-IL5

  • Mepolizumab

D. Supportive Therapy

  • Bronchodilators
  • Inhaled corticosteroids
  • Airway clearance techniques

10. Monitoring

Key Marker → Total IgE

  • Baseline → follow every 6–8 weeks
  • Rise >50% → relapse

Imaging

  • Repeat HRCT if clinical worsening

11. Complications

  • Central bronchiectasis (irreversible)
  • Pulmonary fibrosis
  • Chronic respiratory failure
  • Cor pulmonale