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Etymology

Derived from the Greek “emphysan,” meaning “to inflate.” “Panlobular” refers to the uniform involvement of the entire acinus or lobule.

AKA

  • Panacinar Emphysema
  • Panlobular Pulmonary Emphysema

What is it?

A type of emphysema characterized by uniform destruction and enlargement of the alveoli throughout the entire acinus, typically involving the lower lobes.

Caused by:

  1. Inherited:
    • Alpha-1 Antitrypsin Deficiency (AATD) (most common).
  2. Inflammation/Immune:
    • Chronic inflammation due to cigarette smoking (less common than centrilobular emphysema in smokers).
  3. Metabolic:
    • Rarely associated with metabolic syndromes or oxidative stress-related disorders.

Resulting in:

  • Progressive destruction of alveolar walls.
  • Loss of elastic recoil.
  • Air trapping and hyperinflation.
  • V/Q mismatch and hypoxemia.

Structural changes:

  • Uniform enlargement of alveolar spaces.
  • Loss of alveolar septa and capillary beds.
  • Lung hyperinflation predominantly in the lower lobes.

Pathophysiology:

  • Reduced alpha-1 antitrypsin leads to unchecked elastase activity, causing destruction of elastin in alveolar walls.
  • Smoking exacerbates oxidative stress, further degrading elastin.

Pathology:

  • Gross: Diffusely enlarged and overinflated lungs, especially in the lower zones.
  • Microscopic: Alveolar wall destruction and obliteration of capillaries.

Diagnosis:

  • Suspected in individuals with dyspnea, especially young or non-smokers with AATD.
  • Confirmed via imaging, laboratory testing for AAT levels, and genetic studies.

Clinical:

  • Symptoms: Progressive dyspnea, exercise intolerance, minimal sputum production.
  • Signs: Barrel chest, hyper-resonance, and diminished breath sounds.

Radiology:

  • CXR:
    • Findings: Hyperinflation, flattened diaphragms, decreased vascular markings in lower lobes.
    • Associated Findings: Rarely, concurrent bullae.
  • CT:
    • Parts: Lower lobes predominantly affected.
    • Size: Uniform enlargement of acini.
    • Shape: Diffuse destruction without focal nodules.
    • Position: Diffuse, more prominent basally.
    • Character: Loss of lung markings; diffuse hypoattenuation.
    • Time: Chronic, progressive changes.
    • Associated Findings: Possible small bullae, vascular attenuation.
  • Other Imaging Modalities:
    • MRI: Limited role; can show loss of parenchymal integrity.
    • PET-CT: Sometimes used to assess concurrent inflammatory processes.
    • US: Not typically used.
    • Angio: May show vascular pruning in advanced cases.

Pulmonary Function Tests (PFTs)

  • Obstructive pattern with reduced FEV1/FVC ratio.
  • Increased total lung capacity (TLC) and residual volume (RV).
  • Reduced diffusing capacity of the lung for carbon monoxide (DLCO).

Management:

  1. Lifestyle modifications: Smoking cessation.
  2. Medical therapy:
    • Inhaled bronchodilators and corticosteroids.
    • AAT replacement therapy in AATD cases.
  3. Pulmonary rehabilitation: Exercise and breathing techniques.
  4. Advanced therapy:
    • Lung volume reduction surgery or lung transplantation for advanced cases.

Recommendations:

  • Early testing for AAT levels in young patients or those with a family history.
  • Smoking cessation is critical to slow progression.
  • Regular follow-up with imaging and PFTs.

Key Points and Pearls:

  • Panlobular emphysema is classically associated with alpha-1 antitrypsin deficiency.
  • Lower lobe predominance differentiates it from centrilobular emphysema, which affects upper lobes.
  • Early diagnosis and management can significantly improve quality of life.