Peripheral (Subpleural) Lung Disease Distribution

Peripheral (Subpleural) Lung Disease Distribution
Jonathan H. Chung, MD
DIFFERENTIAL DIAGNOSIS
Common
  • Pneumonia
  • Lung Cancer
  • Rounded Atelectasis
  • Septic Emboli
  • Pulmonary Contusions
Less Common
  • Pulmonary Infarction
  • Cryptogenic Organizing Pneumonia
  • Chronic Eosinophilic Pneumonia
  • Usual Interstitial Pneumonitis
  • Desquamative Interstitial Pneumonia
Rare but Important
  • Amyloidosis
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
  • Acute vs. chronic
    • Acute abnormalities
      • Pneumonia
      • Septic emboli
      • Pulmonary infarctions (within 12-24 hours of embolic event); slow resolution
    • Chronic abnormalities
      • Lung cancer
      • Round atelectasis
      • Cryptogenic organizing pneumonia
      • Chronic eosinophilic pneumonia
      • Chronic interstitial lung diseases
Helpful Clues for Common Diagnoses
  • Pneumonia
    • Airspace opacities: Ground-glass opacities to dense consolidation
    • Reactive lymphadenopathy; very large lymph nodes unusual
    • Parapneumonic pleural effusion or empyema
    • Correlation with sputum, WBC count, and clinical presentation paramount
  • Lung Cancer
    • Suggestive findings include
      • Focal mass-like consolidation larger than 3 cm
      • Spiculated margins
      • Thick-walled or nodular cavitation
      • Large hilar &/or mediastinal lymphadenopathy (> 2 cm)
      • Concomitant emphysema and smoking history
  • Rounded Atelectasis
    • Definitive diagnosis on CT requires 4 findings
      • Pleural abnormality: Pleural thickening, pleural effusion, or pleural plaque
      • Broad-based intimate attachment of mass-like consolidation to pleural abnormality
      • Volume loss
      • Comet tail (or hurricane) sign: Swirling of bronchovasculature into mass-like consolidation
  • Septic Emboli
    • Patients with indwelling catheters or IV drug users at risk
    • Multiple peripheral/subpleural nodules and wedge-shaped consolidation with rapid cavitation
    • Feeding vessel sign: Vessel leads directly to peripheral nodule or wedge-shaped consolidation
    • Exudative pleural effusion, often loculated
  • Pulmonary Contusions
    • Acute trauma clinical setting
    • Peripheral
    • Under point of blunt kinetic energy absorption
      • Often lateral portions of lung away from overlying musculature
    • Overlying rib fractures
      • Can occur without rib fractures in children and young adults
    • Appear at time of injury
    • Resolve in 3-5 days
    • Associated with other injuries but can be isolated
    • Associated with ballistic injuries
Helpful Clues for Less Common Diagnoses
  • Pulmonary Infarction
    • Most often from pulmonary arterial embolism
    • Often in setting of superimposed cardiac dysfunction (cardiomyopathy, congestive heart failure)
      • Both pulmonary and bronchial arterial supply to lung reduced
    • Lower lung predominant, peripheral/subpleural, wedge-shaped consolidation
    • Resolves over months (retains its original shape) rather than patchy resolution as in pneumonia
  • Cryptogenic Organizing Pneumonia
    • Bilateral, basal-predominant, peripheral and peribronchovascular consolidation
    • Scattered areas of ground-glass opacities and nodules
    • Atoll sign (a.k.a. reversed halo sign): Central ground-glass opacity surrounded by rim of consolidation
    • Perilobular opacities: Ill-defined opacities outlining interlobular septa of secondary pulmonary lobule
  • Chronic Eosinophilic Pneumonia
    • Peripheral, upper lung consolidation (so-called photographic negative of pulmonary edema)
    • Ground-glass opacities do not predominate
    • Waxing and waning disease course
    • Tendency to resolve centripetally (from outer to inner)
    • Residual band of linear opacities parallels chest wall late in evolution of disease
  • Usual Interstitial Pneumonitis
    • Peripheral and basal predominant distribution; costophrenic angles most affected
    • Volume loss
    • Reticular opacities, linear opacities, architectural distortion
    • Traction bronchiectasis and honeycombing
    • Ground-glass opacities do not predominate
    • Mild mediastinal lymphadenopathy not uncommon
  • Desquamative Interstitial Pneumonia
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Aug 8, 2016 | Posted by in CARDIOLOGY | Comments Off on Peripheral (Subpleural) Lung Disease Distribution

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