What is centrolobular emphysema?

Centrolobular Emphysema

Centrolobular emphysema (CLE) is a specific type of emphysema characterized by destruction of respiratory bronchioles, alveolar ducts, and alveoli at the center of the acinus, while surrounding alveoli remain intact. 1

Pathological Features

• CLE is one of the major patterns of emphysema, distinct from panacinar and paraseptal emphysema, with specific anatomical and functional consequences 1
• It primarily affects the central portion of the secondary pulmonary lobule, sparing the peripheral alveoli 1
• CLE is associated with more small airways disease and less loss of elastic recoil for any level of respiratory function compared to other emphysema types 1
• Morphologically, CLE can be classified into three subtypes based on CT-pathologic correlations 2:
  • Type A: round or oval shape with well-defined borders (primarily related to bronchiolar dilatation)
  • Type B: polygonal or irregular shape with ill-defined borders (<5mm diameter), related to destruction of proximal alveolar ducts
  • Type C: irregular shape with ill-defined borders (≥5mm diameter), related to destruction of distal alveolar ducts

Clinical and Physiological Implications

• CLE is strongly associated with cigarette smoking history (+21 pack-years compared to controls) 3
• Patients with CLE experience greater dyspnea, reduced exercise capacity (measured by six-minute walk distance), and greater hyperinflation compared to those without emphysema 3
• CLE demonstrates more significant airway abnormalities than other emphysema types, with thicker, narrower, and more reactive membranous bronchioles 4
• Terminal bronchioles are significantly reduced in number and cross-sectional lumen area in CLE-dominant regions compared to mild emphysema or paraseptal emphysema-dominant regions 5
• CLE is associated with steeper declines in diffusing capacity (DLCO) and transfer coefficient (KCO) across all GOLD stages of COPD, independent of age, sex, height, and smoking history 6
• Moderate or severe CLE is linked to accelerated FEV1 decline and higher 10-year mortality in patients with severe COPD (GOLD stage 3 or higher) 6

Comparison with Other Emphysema Types

• Unlike panacinar emphysema (which affects the entire acinus uniformly), CLE has uneven destruction focused on the central portion of the lobule 1, 4
• Unlike paraseptal emphysema (which occurs adjacent to connective tissue septa), CLE affects the central portions of the secondary lobule 1
• CLE shows greater neutrophilic inflammation compared to paraseptal emphysema 5
• While panacinar emphysema is strongly associated with reduced body mass index, CLE is more strongly associated with smoking history 3
• CLE has a stronger association with longitudinal decline in lung function and mortality compared to paraseptal emphysema 6

Diagnostic Considerations

• High-resolution CT scanning is sufficiently sensitive to diagnose emphysema patterns, including CLE 1
• CLE is the most common type of emphysema in COPD, with Type B (polygonal/irregular shape with ill-defined borders <5mm) being the most prevalent subtype (58% of patients) 2
• CLE can be present in smokers even without spirometric evidence of COPD, which is independently associated with reduced exercise capacity 3

Clinical Significance

• The presence of CLE has important prognostic implications, as it is associated with more rapid decline in diffusing capacity and higher mortality compared to other emphysema subtypes 6
• Recognition of CLE on imaging is important for risk stratification and management planning in patients with COPD 1, 3
• The distinct pathophysiology of CLE (airway-predominant disease) compared to panacinar emphysema (loss of elastic recoil) may have implications for targeted therapeutic approaches 4