Eosinophilic Lung Disease in Children
Eosinophilic Lung Disease in Children
Eosinophilic lung diseases are a diverse group of disorders characterized by the accumulation of eosinophils in the lungs and airways. These conditions can affect children of all ages and can range from acute, self-limiting illnesses to chronic, life-threatening disorders. Understanding these diseases is crucial for pediatricians and pulmonologists to ensure proper diagnosis and management.
Classification
Eosinophilic lung diseases in children can be classified into several categories:
- Primary (idiopathic) eosinophilic lung diseases:
- Acute Eosinophilic Pneumonia (AEP)
- Chronic Eosinophilic Pneumonia (CEP)
- Idiopathic Hypereosinophilic Syndrome (HES)
- Secondary eosinophilic lung diseases:
- Allergic: Asthma, Allergic Bronchopulmonary Aspergillosis (ABPA)
- Parasitic infections: Toxocariasis, Ascariasis
- Drug-induced: Antibiotics, NSAIDs, antiepileptics
- Connective tissue disorders: Churg-Strauss Syndrome (EGPA)
- Malignancy-associated
Pathophysiology
The pathophysiology of eosinophilic lung diseases involves:
- Recruitment and activation of eosinophils in the lungs
- Release of pro-inflammatory mediators (e.g., major basic protein, eosinophil cationic protein)
- Tissue damage and remodeling due to chronic inflammation
- Overproduction of Th2 cytokines (IL-4, IL-5, IL-13) leading to eosinophil proliferation and survival
- Impaired eosinophil apoptosis and clearance
The specific triggers and mechanisms vary depending on the underlying cause of the eosinophilic lung disease.
Clinical Presentation
The clinical presentation of eosinophilic lung diseases in children can vary widely, but common symptoms include:
- Cough (often nonproductive)
- Dyspnea or shortness of breath
- Wheezing
- Chest pain
- Fever (more common in acute presentations)
- Weight loss and failure to thrive (in chronic cases)
- Fatigue and malaise
Specific presentations may include:
- Acute Eosinophilic Pneumonia: Rapid onset of respiratory symptoms with fever
- Chronic Eosinophilic Pneumonia: Gradual onset with constitutional symptoms
- ABPA: Recurrent pulmonary infiltrates and bronchiectasis in patients with asthma or cystic fibrosis
- Churg-Strauss Syndrome: Asthma, sinusitis, and systemic vasculitis
Diagnosis
Diagnosing eosinophilic lung diseases in children requires a combination of clinical, laboratory, and imaging studies:
- Blood tests:
- Complete blood count with differential (elevated eosinophil count)
- Serum IgE levels
- Aspergillus-specific IgE and IgG (for ABPA)
- ANCA (for Churg-Strauss Syndrome)
- Imaging:
- Chest X-ray: May show patchy or diffuse infiltrates
- High-resolution CT scan: More detailed assessment of lung involvement
- Pulmonary function tests: Often show restrictive or mixed patterns
- Bronchoscopy with bronchoalveolar lavage (BAL):
- BAL fluid analysis showing elevated eosinophil percentage (>25%)
- Helps exclude infectious causes
- Lung biopsy: May be necessary in unclear cases to confirm diagnosis and exclude other conditions
- Specific tests for suspected underlying causes:
- Parasitic serologies
- Allergy skin tests or specific IgE levels
- Drug provocation tests (if drug-induced eosinophilia is suspected)
Treatment
Treatment of eosinophilic lung diseases in children depends on the underlying cause and severity of the condition:
- Corticosteroids:
- Mainstay of treatment for most eosinophilic lung diseases
- Oral prednisone (1-2 mg/kg/day) for acute presentations, tapered over weeks to months
- Inhaled corticosteroids for maintenance in some cases
- Biological agents:
- Mepolizumab or benralizumab (anti-IL-5 therapy) for severe eosinophilic asthma or HES
- Omalizumab (anti-IgE) for ABPA
- Immunosuppressants:
- Azathioprine, mycophenolate mofetil, or methotrexate for steroid-sparing in chronic cases
- Anthelmintic treatment for parasitic causes
- Discontinuation of offending drugs in drug-induced eosinophilia
- Management of underlying conditions (e.g., asthma, allergies)
- Supportive care:
- Oxygen therapy
- Bronchodilators for associated airway obstruction
- Nutritional support
Prognosis
The prognosis of eosinophilic lung diseases in children varies depending on the specific condition and its underlying cause:
- Acute Eosinophilic Pneumonia: Generally good prognosis with appropriate treatment
- Chronic Eosinophilic Pneumonia: May require long-term treatment but often has a favorable outcome
- ABPA: Can lead to bronchiectasis and fibrosis if not adequately managed
- Churg-Strauss Syndrome: Requires long-term immunosuppression; prognosis depends on organ involvement
- Parasitic causes: Excellent prognosis with appropriate antiparasitic treatment
- Drug-induced eosinophilia: Usually resolves with discontinuation of the offending drug
Long-term follow-up is essential for most eosinophilic lung diseases to monitor for relapses and adjust treatment as needed. Early diagnosis and appropriate management are crucial for preventing long-term complications such as lung fibrosis or chronic respiratory insufficiency.
Eosinophilic Lung Disease in Children
- What is the defining characteristic of eosinophilic lung diseases?
Increased number of eosinophils in lung tissue or bronchoalveolar lavage fluid - What is Löffler's syndrome?
A transient eosinophilic pneumonia associated with parasitic infections - What is the most common cause of chronic eosinophilic pneumonia in children?
Idiopathic (no known cause) - What is the characteristic radiographic finding in chronic eosinophilic pneumonia?
Peripheral pulmonary infiltrates ("photographic negative" of pulmonary edema) - What is the typical blood eosinophil count in eosinophilic lung diseases?
Greater than 1000 cells/μL - What is the gold standard for diagnosing eosinophilic lung disease?
Lung biopsy showing eosinophilic infiltration - What is the role of bronchoalveolar lavage in diagnosing eosinophilic lung disease?
To demonstrate increased eosinophil percentage (>25%) in BAL fluid - What is the primary treatment for most eosinophilic lung diseases?
Systemic corticosteroids - What is hypereosinophilic syndrome?
A group of disorders characterized by persistent eosinophilia affecting multiple organs - What is the role of ANCA testing in eosinophilic lung diseases?
To rule out eosinophilic granulomatosis with polyangiitis (EGPA, formerly Churg-Strauss syndrome) - What is tropical pulmonary eosinophilia?
A form of eosinophilic lung disease caused by filarial parasites - What is the most common symptom of eosinophilic lung disease in children?
Chronic cough - What is the role of helminths in eosinophilic lung diseases?
They can cause pulmonary eosinophilia during larval migration through the lungs - What is acute eosinophilic pneumonia?
A rapidly progressive form of eosinophilic lung disease often requiring mechanical ventilation - What is the typical duration of steroid treatment for chronic eosinophilic pneumonia?
Prolonged (months to years) with gradual tapering - What is the role of mepolizumab in treating eosinophilic lung diseases?
As a steroid-sparing agent in refractory cases - What is the significance of IgE levels in eosinophilic lung diseases?
Often elevated, but not diagnostic - What is the role of pulmonary function tests in eosinophilic lung diseases?
To assess for restrictive or mixed obstructive-restrictive patterns - What is simple pulmonary eosinophilia (Löffler's syndrome)?
A self-limiting condition characterized by transient pulmonary infiltrates and eosinophilia - What is the prognosis for most children with eosinophilic lung diseases?
Generally good with appropriate treatment, but some may have recurrent episodes - What is the role of bronchial challenge testing in eosinophilic lung diseases?
To assess for bronchial hyperresponsiveness, which is common in these conditions - What is the significance of ground-glass opacities on chest CT in eosinophilic lung diseases?
They often indicate active inflammation - What is eosinophilic granulomatosis with polyangiitis (EGPA)?
A systemic vasculitis characterized by asthma, eosinophilia, and small vessel vasculitis - What is the role of inhaled corticosteroids in treating eosinophilic lung diseases?
Generally limited, as most forms require systemic therapy - What is the significance of eosinophilic pleural effusions?
They can occur in some eosinophilic lung diseases and may require drainage - What is the role of genetic testing in eosinophilic lung diseases?
To identify rare genetic causes such as STAT3 gain-of-function mutations - What is the importance of monitoring for systemic complications in eosinophilic lung diseases?
Some forms can affect multiple organs, requiring comprehensive follow-up - What is the role of leukotriene modifiers in treating eosinophilic lung diseases?
They may be helpful in some cases, particularly those associated with asthma - What is the significance of BAL eosinophilia without peripheral blood eosinophilia?
It can occur in some forms of eosinophilic lung disease and still requires evaluation - What is the role of echocardiography in evaluating children with eosinophilic lung diseases?
To assess for pulmonary hypertension and cardiac involvement in hypereosinophilic syndrome
