Panbronchiolitis - Diffuse

Diffuse Panbronchiolitis (DPB) is a chronic inflammatory disease of the respiratory bronchioles, predominantly affecting the lower lungs, characterized by chronic cough, sputum production, and progressive airflow obstruction. It is more common in East Asian populations.

Definition

Epidemiology

Predominantly affects adults of East Asian descent, especially Japanese and Koreans
Male-to-female ratio approximately 1.5–2:1
Typically manifests in adults aged 40–60 years
Rare in Western populations
Associated with chronic sinusitis in most cases

Etiology

Exact cause unknown; genetic predisposition suggested (HLA-B54 in Japanese patients)
Chronic bacterial infection, especially Haemophilus influenzae, may contribute
Environmental factors or chronic exposure may play a role
Immune system dysregulation implicated in pathogenesis
Smoking is not a primary risk factor but may exacerbate disease

Pathophysiology

Chronic inflammation of respiratory bronchioles with lymphocytic and neutrophilic infiltration
Bronchial wall thickening and peribronchiolar fibrosis
Progressive airflow obstruction due to small airway involvement
Excessive mucus production leads to airway plugging
Secondary infection contributes to chronic symptoms
Impaired mucociliary clearance exacerbates bacterial colonization
Chronic inflammation can eventually cause bronchiectasis