Bronchiolitis: adopting a unifying definition and a comprehensive etiological classification

Area of Science:

• Pulmonology
• Pathology

Background:

• Bronchiolitis is an inflammatory and fibrosing condition affecting small airways.
• It can be secondary to various known causes or primary/idiopathic.
• Chronic bronchiolitis can lead to irreversible airway damage.

Purpose of the Study:

• To differentiate between primary and secondary bronchiolitis.
• To outline the diverse etiologies and clinical entities associated with bronchiolitis.
• To describe the clinical significance and outcomes of bronchiolitis.

Main Methods:

• Review of existing literature and clinical data.
• Classification of bronchiolitis based on etiology and clinical presentation.
• Pathological description of bronchiolitis and its consequences.

Main Results:

• Secondary bronchiolitis is common, associated with infections, smoking, and other factors.
• Primary/idiopathic bronchiolitis is rare and encompasses distinct clinicopathologic entities.
• Chronic bronchiolitis can cause significant morbidity and mortality, potentially leading to bronchiectasis.

Conclusions:

• Bronchiolitis classification is crucial for understanding its diverse origins and clinical impact.
• Early recognition and management are important for chronic forms to prevent progression.
• Bronchiolitis represents a spectrum of airway diseases with varying prognoses.