Interstitial Lung Disease in Children
Introduction to Interstitial Lung Disease in Children
Interstitial Lung Disease (ILD) in children, also known as chILD (childhood ILD), refers to a heterogeneous group of rare lung disorders characterized by inflammation and fibrosis of the lung parenchyma. These disorders lead to impaired gas exchange, restrictive physiology, and diffuse radiographic abnormalities. Pediatric ILD differs from adult ILD in its etiology, clinical presentation, and management, necessitating a specialized approach to diagnosis and treatment.
Classification of Interstitial Lung Disease in Children
The classification of chILD has evolved over time. A widely accepted classification system is based on the etiology and age of onset:
- Disorders more prevalent in infancy:
- Diffuse developmental disorders (e.g., alveolar capillary dysplasia)
- Growth abnormalities (e.g., chromosomal disorders, congenital heart disease)
- Specific conditions of undefined etiology (e.g., neuroendocrine cell hyperplasia of infancy)
- Surfactant dysfunction disorders
- Disorders not specific to infancy:
- Disorders of the normal host (e.g., hypersensitivity pneumonitis, aspiration syndromes)
- Disorders related to systemic diseases (e.g., connective tissue diseases, storage diseases)
- Disorders of the immunocompromised host
- Unclassified disorders
Etiology of Interstitial Lung Disease in Children
- Genetic Disorders:
- Surfactant protein deficiencies (SFTPB, SFTPC, ABCA3 mutations)
- Telomere biology disorders
- COPA syndrome
- Systemic Diseases:
- Connective tissue diseases (e.g., juvenile systemic sclerosis, dermatomyositis)
- Sarcoidosis
- Langerhans cell histiocytosis
- Immune-Mediated Disorders:
- Hypersensitivity pneumonitis
- Eosinophilic lung diseases
- Environmental Exposures:
- Toxic inhalation
- Radiation-induced pneumonitis
- Infectious Causes: Chronic infections (e.g., atypical mycobacteria)
- Iatrogenic Causes: Drug-induced pneumonitis
- Idiopathic Disorders:
- Neuroendocrine cell hyperplasia of infancy (NEHI)
- Pulmonary interstitial glycogenosis (PIG)
Clinical Presentation of Interstitial Lung Disease in Children
- Respiratory Symptoms:
- Tachypnea
- Dyspnea
- Chronic cough
- Recurrent respiratory infections
- Systemic Symptoms:
- Failure to thrive
- Poor weight gain
- Fatigue
- Exercise intolerance
- Physical Examination Findings:
- Tachypnea and increased work of breathing
- Chest wall retractions
- Digital clubbing (in chronic cases)
- Fine crackles on auscultation
- Signs of cor pulmonale in advanced cases
- Associated Features: Dependent on underlying etiology (e.g., rash in connective tissue diseases)
Diagnosis of Interstitial Lung Disease in Children
- Clinical History and Physical Examination: Essential for identifying potential causes and assessing severity.
- Imaging Studies:
- Chest X-ray: Often shows diffuse infiltrates but may be normal in early stages
- High-resolution CT (HRCT): Gold standard for imaging, showing characteristic patterns
- Pulmonary Function Tests:
- Spirometry: Usually shows restrictive pattern
- Diffusion capacity (DLCO): Often reduced
- 6-minute walk test: To assess exercise capacity and oxygen desaturation
- Laboratory Tests:
- Complete blood count
- Inflammatory markers (ESR, CRP)
- Autoimmune panel for suspected connective tissue diseases
- Genetic testing for suspected inherited disorders
- Bronchoscopy with Bronchoalveolar Lavage (BAL):
- To exclude infection
- To assess cellularity and possible etiologies (e.g., hemosiderin-laden macrophages in pulmonary hemosiderosis)
- Lung Biopsy:
- Often necessary for definitive diagnosis
- Can be performed via video-assisted thoracoscopic surgery (VATS) or open lung biopsy
- Echocardiography: To assess for pulmonary hypertension
- Sweat Chloride Test: To rule out cystic fibrosis
Management of Interstitial Lung Disease in Children
- Supportive Care:
- Oxygen therapy
- Nutritional support
- Vaccination against respiratory pathogens
- Treatment of gastroesophageal reflux if present
- Pharmacological Treatment:
- Corticosteroids: Often used as first-line therapy
- Immunosuppressants (e.g., azathioprine, mycophenolate mofetil): For steroid-sparing or in specific conditions
- Hydroxychloroquine: Particularly in surfactant protein C mutations
- Macrolides: For their anti-inflammatory properties in some cases
- Management of Specific Etiologies:
- Avoidance of triggering antigens in hypersensitivity pneumonitis
- Treatment of underlying systemic diseases
- Targeted therapies for specific genetic disorders
- Pulmonary Rehabilitation: To improve exercise tolerance and quality of life
- Psychosocial Support: For patients and families dealing with chronic illness
- Lung Transplantation: Considered in severe, progressive cases unresponsive to medical management
Prognosis of Interstitial Lung Disease in Children
- Overall Prognosis: Highly variable, depending on the underlying etiology and severity at presentation
- Factors Affecting Prognosis:
- Specific diagnosis
- Age at onset (infantile onset often has poorer prognosis)
- Presence of pulmonary hypertension
- Response to treatment
- Disease Course:
- Some forms (e.g., NEHI) may improve over time
- Others (e.g., surfactant protein B deficiency) are progressive and may require lung transplantation
- Long-term Complications:
- Pulmonary hypertension
- Cor pulmonale
- Growth failure
- Neurodevelopmental delays
- Follow-up: Regular monitoring of lung function, growth, and development is essential
Interstitial Lung Disease in Children
- What is the primary characteristic of interstitial lung disease (ILD) in children?
Diffuse lung inflammation and fibrosis affecting the interstitium - What is the most common symptom of ILD in children?
Chronic cough - What physical examination finding is common in children with ILD?
Clubbing of fingers and toes - What is the gold standard for diagnosing ILD in children?
Lung biopsy - What imaging modality is most useful for evaluating ILD in children?
High-resolution computed tomography (HRCT) - What is surfactant dysfunction disorder?
A genetic condition causing ILD due to abnormal surfactant production or function - What gene mutation is associated with surfactant protein B deficiency?
SFTPB gene mutation - What is neuroendocrine cell hyperplasia of infancy (NEHI)?
A form of childhood ILD characterized by increased pulmonary neuroendocrine cells - What is the typical age of onset for NEHI?
Usually before 2 years of age - What pulmonary function test finding is common in children with ILD?
Restrictive pattern with decreased diffusion capacity - What is the role of bronchoalveolar lavage in diagnosing childhood ILD?
To assess cellularity and rule out infections - What is the most common treatment for ILD in children?
Corticosteroids - What is the role of hydroxychloroquine in treating childhood ILD?
As a steroid-sparing agent, particularly effective in some forms of surfactant dysfunction - What is bronchiolitis obliterans?
A form of ILD characterized by obstruction and fibrosis of small airways - What is a common cause of bronchiolitis obliterans in children?
Post-infectious, particularly after adenovirus infection - What is the role of genetic testing in evaluating childhood ILD?
To identify specific genetic mutations associated with surfactant dysfunction disorders - What is pulmonary alveolar proteinosis?
A rare ILD characterized by accumulation of surfactant proteins in alveoli - What is the typical treatment for pulmonary alveolar proteinosis?
Whole lung lavage - What is the role of lung transplantation in childhood ILD?
A last resort for severe, progressive disease unresponsive to other treatments - What is the prognosis for children with ILD?
Variable, depending on the specific form and severity, ranging from resolution to progressive fibrosis - What is hypersensitivity pneumonitis?
An ILD caused by repeated inhalation of organic antigens, leading to an allergic reaction in the lungs - What environmental exposure is commonly associated with hypersensitivity pneumonitis in children?
Bird proteins (e.g., from pet birds or feather bedding) - What is the role of pulse oximetry in monitoring children with ILD?
To assess for hypoxemia, particularly during exercise or sleep - What is the significance of failure to thrive in children with ILD?
It often indicates severe disease and increased work of breathing - What is the role of echocardiography in evaluating children with ILD?
To assess for pulmonary hypertension, a common complication of ILD - What is the typical HRCT finding in children with ILD?
Ground-glass opacities, often with a geographic distribution - What is follicular bronchiolitis?
A form of ILD characterized by hyperplasia of bronchus-associated lymphoid tissue - What systemic diseases can cause ILD in children?
Connective tissue diseases such as systemic lupus erythematosus and juvenile dermatomyositis - What is the role of inhaled corticosteroids in treating childhood ILD?
Generally limited, as most forms of ILD require systemic therapy - What is the importance of genetic counseling in families with a child diagnosed with ILD?
To discuss inheritance patterns and risks for future pregnancies, particularly in genetic forms of ILD
