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Difficulty: Very hardPediatric Respiratory Disorders

A 15-year-old adolescent with cystic fibrosis and pancreatic insufficiency is evaluated in the outpatient pulmonary clinic for a 4-week history of worsening productive cough, malaise, and subjective low-grade fevers. He reports expectorating thick, brownish, plug-like sputum. His daily maintenance regimen of dornase alfa, hypertonic saline, and chest physiotherapy has not alleviated the symptoms. Pulmonary function testing performed today shows a forced expiratory volume in 1 second (FEV1) of 60% of predicted, a significant decline from his baseline of 84% recorded two months ago. Vital signs show an oxygen saturation of 95% on ambient air. Lung auscultation reveals prominent bilateral expiratory wheezes and coarse upper lobe crackles. A complete blood count is notable for an absolute eosinophil count of 1,250/mm³. Total serum IgE is markedly elevated at 1,650 IU/mL. High-resolution computed tomography of the chest demonstrates new upper lobe central bronchiectasis with scattered mucous plugging and fleeting infiltrates. Which of the following are indicated in the initial pharmacological management of this patient's current condition? (Select all that apply)

  1. Oral prednisoneAnswer
  2. Oral itraconazoleAnswer
  3. C
    Intravenous cefepime and vancomycin
  4. D
    Nebulized racemic epinephrine
  5. E
    Intravenous furosemide

Answer

The correct management bundle includes Oral prednisone and Oral itraconazole.
This patient's clinical and diagnostic profile is pathognomonic for Allergic Bronchopulmonary Aspergillosis (ABPA), a severe hypersensitivity reaction to Aspergillus colonization that frequently complicates cystic fibrosis and severe asthma. The diagnostic criteria for ABPA include a predisposing condition, elevated total serum IgE (typically > 1,000 IU/mL), peripheral eosinophilia, and radiographic findings of central bronchiectasis or fleeting infiltrates. The mainstay of initial therapy involves suppressing the exaggerated immune response with systemic corticosteroids (e.g., oral prednisone). Additionally, oral azole antifungals (e.g., itraconazole) are indicated to decrease the airway fungal burden, thereby reducing the antigenic stimulus and functioning as a steroid-sparing agent.

Step-by-Step Solution

1
Analyze the clinical presentation and laboratory findings.
The patient has cystic fibrosis and presents with worsened cough, thick brownish sputum, a drop in FEV1, wheezing, peripheral eosinophilia, and a total IgE > 1,000 IU/mL.
Identifying the classic triad of CF, markedly elevated IgE, and peripheral eosinophilia is essential to suspect a specific hypersensitivity reaction rather than a standard bacterial exacerbation.
2
Interpret the high-resolution computed tomography (HRCT) findings.
The HRCT shows central bronchiectasis, mucous plugging, and fleeting infiltrates.
These are the pathognomonic radiologic features that, combined with the lab results, confirm the diagnosis of Allergic Bronchopulmonary Aspergillosis (ABPA).
3
Determine the appropriate pharmacologic management bundle for ABPA.
Systemic corticosteroids (e.g., oral prednisone) and an oral antifungal (e.g., itraconazole) are the treatments of choice.
Steroids suppress the intense Th2-mediated hypersensitivity response, while the antifungal agent reduces the colonization burden of Aspergillus, acting as a steroid-sparing agent and reducing ongoing antigenic stimulation.

Key Concept

Allergic Bronchopulmonary Aspergillosis (ABPA) in patients with cystic fibrosis is characterized by an exaggerated hypersensitivity response to Aspergillus species, presenting with brownish sputum, elevated IgE, eosinophilia, and central bronchiectasis. It requires multi-modal treatment with systemic corticosteroids and oral azole antifungals.
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Pediatric Respiratory Disorders

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