Allergic Bronchopulmonary Aspergillosis in Children

Allergic Bronchopulmonary Aspergillosis in Children

Allergic Bronchopulmonary Aspergillosis (ABPA) is a complex hypersensitivity reaction to the fungus Aspergillus fumigatus, primarily affecting children with asthma or cystic fibrosis. It is characterized by recurrent pulmonary infiltrates, bronchiectasis, and potential progression to pulmonary fibrosis if left untreated.

Pathophysiology

ABPA results from a hypersensitivity reaction to Aspergillus antigens, involving both type I (IgE-mediated) and type III (immune complex-mediated) reactions. The process involves:

  • Colonization of the airways by Aspergillus fumigatus
  • Release of antigenic substances triggering an allergic response
  • Production of specific IgE and IgG antibodies
  • Activation of inflammatory cells, particularly eosinophils
  • Airway damage and bronchiectasis due to persistent inflammation

Clinical Presentation

Children with ABPA may present with:

  • Worsening asthma symptoms or increased inhaler use
  • Recurrent pulmonary infiltrates
  • Productive cough with brownish mucus plugs
  • Wheezing and chest tightness
  • Fever and malaise
  • Hemoptysis (rare in children)

In children with cystic fibrosis, ABPA can lead to more frequent exacerbations and accelerated decline in lung function.

Diagnosis

Diagnosis of ABPA in children requires a combination of clinical, radiological, and immunological criteria:

  1. Asthma or cystic fibrosis
  2. Elevated total serum IgE (>1000 IU/mL)
  3. Positive skin prick test or specific IgE to Aspergillus fumigatus
  4. Elevated Aspergillus-specific IgG or precipitating antibodies
  5. Pulmonary infiltrates on chest radiograph or high-resolution CT
  6. Peripheral blood eosinophilia (>500 cells/μL)
  7. Central bronchiectasis on CT (not always present in children)

Additional tests may include:

  • Sputum culture for Aspergillus
  • Pulmonary function tests showing obstructive pattern
  • Serum galactomannan or (1,3)-β-D-glucan assay

Treatment

Management of ABPA in children involves:

  1. Systemic corticosteroids:
    • Prednisone 0.5-1 mg/kg/day for 2 weeks, then tapered over 3-6 months
    • Aim to reduce inflammation and prevent lung damage
  2. Antifungal therapy:
    • Itraconazole (5-10 mg/kg/day) or voriconazole for 3-6 months
    • Reduces fungal burden and decreases antigenic stimulation
  3. Omalizumab (anti-IgE therapy):
    • Considered in refractory cases or steroid-dependent patients
    • Dosing based on weight and serum IgE levels
  4. Management of underlying asthma or cystic fibrosis
  5. Pulmonary rehabilitation and airway clearance techniques
  6. Regular follow-up with monitoring of symptoms, lung function, and serum IgE levels

Prognosis

With proper management, the prognosis for children with ABPA is generally good. However, factors affecting prognosis include:

  • Early diagnosis and treatment initiation
  • Adherence to therapy
  • Frequency and severity of exacerbations
  • Presence and extent of bronchiectasis
  • Underlying lung disease (asthma or cystic fibrosis) severity

Long-term complications may include:

  • Persistent airflow obstruction
  • Progressive bronchiectasis
  • Pulmonary fibrosis (in severe, untreated cases)

Regular follow-up and adjustment of treatment as needed are crucial for optimizing outcomes in pediatric ABPA patients.



Allergic Bronchopulmonary Aspergillosis in Children
  1. What is Allergic Bronchopulmonary Aspergillosis (ABPA)?
    A hypersensitivity reaction to Aspergillus species colonizing the airways
  2. What are the two most common underlying conditions associated with ABPA in children?
    Cystic fibrosis and asthma
  3. What is the most common causative agent of ABPA?
    Aspergillus fumigatus
  4. What type of hypersensitivity reaction is primarily involved in ABPA?
    Type I (IgE-mediated) and Type III (immune complex) hypersensitivity reactions
  5. What is the characteristic finding on chest X-ray in acute ABPA?
    Fleeting pulmonary infiltrates
  6. What is the pathognomonic finding on chest CT in ABPA?
    Central bronchiectasis
  7. What blood test is crucial for diagnosing ABPA?
    Elevated total serum IgE levels
  8. What is the typical eosinophil count in peripheral blood in ABPA?
    Elevated (>500 cells/μL)
  9. What skin test is used to support the diagnosis of ABPA?
    Immediate cutaneous reactivity to Aspergillus antigens
  10. What is the role of specific IgE and IgG antibodies to A. fumigatus in ABPA diagnosis?
    Elevated levels support the diagnosis
  11. What is the primary treatment for acute exacerbations of ABPA?
    Systemic corticosteroids
  12. What antifungal agent is commonly used in the treatment of ABPA?
    Itraconazole
  13. What is the role of omalizumab in ABPA treatment?
    As a steroid-sparing agent in refractory cases
  14. What is mucoid impaction in ABPA?
    Accumulation of thick, sticky mucus plugs in the bronchi
  15. What is the "finger-in-glove" sign on chest imaging?
    A characteristic finding of mucoid impaction in bronchi
  16. What is the most serious long-term complication of ABPA?
    Pulmonary fibrosis
  17. How is ABPA classified based on IgE levels?
    ABPA-S (IgE <1000 IU/mL) and ABPA-CB (IgE >1000 IU/mL)
  18. What is the recommended frequency of IgE level monitoring in ABPA patients?
    Every 1-2 months during tapering of steroids, then every 3-6 months
  19. What is the role of bronchoscopy in ABPA diagnosis?
    To obtain mucus plugs for culture and to rule out other conditions
  20. What is bronchocentric granulomatosis in ABPA?
    A histopathological finding characterized by granulomatous inflammation around airways
  21. What is the significance of Aspergillus precipitins in ABPA diagnosis?
    Their presence supports the diagnosis but is not specific
  22. What is the role of pulmonary function tests in monitoring ABPA?
    To assess for obstructive patterns and track disease progression


Further Reading
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