Pleural Diseases

Pleural Effusions - Water Woes

• Types & Causes:
  • Transudate: ↑ hydrostatic or ↓ oncotic pressure (CHF, cirrhosis, nephrotic).
  • Exudate: ↑ pleural permeability (pneumonia, malignancy, TB, PE).
  • Light's Criteria (Exudate if ≥1): (📌 5-6-2/3)
    • Pleural Fluid Protein/Serum Protein > 0.5
    • Pleural Fluid LDH/Serum LDH > 0.6
    • Pleural Fluid LDH > 2/3 Upper Limit of Normal Serum LDH.
• Imaging:
  • CXR: Costophrenic angle (CPA) blunting (>200ml), meniscus sign, subpulmonic effusion, vanishing tumor (fissural). Lateral decubitus: confirms free fluid.
  • USG: Anechoic (transudate) vs. complex/septated (exudate); ideal for thoracentesis guidance.
  • CT: Loculations, pleural enhancement, underlying lung pathology.

⭐ A subpulmonic effusion can mimic an elevated hemidiaphragm; a lateral decubitus X-ray showing layering of fluid is key for confirmation.

Pneumothorax - Air Scare

• Types:
  • Spontaneous:
    • Primary: No underlying lung disease (e.g., ruptured apical blebs in tall, thin males)
    • Secondary: With underlying lung disease (e.g., COPD, TB, cystic fibrosis)
  • Traumatic: Due to penetrating or blunt chest trauma
  • Iatrogenic: Resulting from medical procedures (e.g., central line insertion, lung biopsy)
• CXR Signs:
  • Visible visceral pleural line (sharp white line of the collapsed lung edge)
  • Absent peripheral lung markings beyond the pleural line
  • Expiratory films: May enhance visibility of small pneumothoraces
  • Deep sulcus sign: On supine CXR, indicates air collection anteroinferiorly, deepening the costophrenic angle

    ⭐ The 'deep sulcus sign' on a supine chest X-ray is a critical indicator of pneumothorax, especially in trauma or ICU patients.

• Tension Pneumothorax (EMERGENCY!):
  • Mediastinal shift (contralateral, away from PTX)
  • Diaphragmatic depression (ipsilateral)
  • ↑ Hyperlucent hemithorax, widened intercostal spaces
• CT Chest:
  • Gold standard for detecting small or loculated pneumothoraces
  • Identifies underlying cause (e.g., bullae, blebs, cysts)

Pleural Infections & Thickening - Gunk & Grime

• Parapneumonic Effusion (PPE): Exudate with pneumonia.
  • Uncomplicated: Free-flowing; antibiotics.
  • Complicated: Loculated; needs drainage.
• Empyema: Pus in pleural space. Criteria:
  • pH < 7.20
  • Glucose < 60 mg/dL
  • LDH > 1000 IU/L
  • Positive Gram stain/culture.
• Imaging (Empyema):
  • CXR: Lenticular opacity.
  • CECT: Split pleura sign, thickened/enhancing pleura, gas.
  • USG: Loculations, septations; guides drainage.

⭐ 'Split pleura sign' (CECT): thickened, enhancing visceral & parietal pleura separated by complex fluid; highly suggestive of empyema.

• Pleural Thickening Causes: Post-infection (TB), asbestos, post-hemothorax, malignancy.
• Pleural Calcification:
  • Asbestos: Parietal/diaphragmatic plaques; spares costophrenic angles/apices.
  • TB: Extensive, visceral; 'empyema necessitans' (pus tracks through chest wall).

Pleural Masses - Lumps & Bumps

⭐ Malignant mesothelioma typically causes circumferential, nodular pleural thickening that encases the lung, often associated with a history of asbestos exposure and may lead to ipsilateral lung volume loss.

• Solitary Fibrous Tumor of Pleura (SFTP)
  • Mostly benign; can be large, pedunculated/sessile.
  • Associations:
    • Hypoglycemia (Doege-Potter syndrome).
    • Hypertrophic osteoarthropathy (Pierre Marie-Bamberger syndrome).
• Lipoma
  • Fat density on CT.

High‑Yield Points - ⚡ Biggest Takeaways

• Pleural effusion: Meniscus sign on CXR; Light's criteria for exudate vs. transudate.
• Pneumothorax: Visceral pleural line visible; tension type is an emergency with mediastinal shift.
• Empyema: Loculated pus in pleural space, requires prompt drainage.
• Hemothorax: Blood in pleural cavity, often post-traumatic; CT density >50 HU.
• Mesothelioma: Aggressive tumor linked to asbestos; causes large unilateral effusion, nodular pleural thickening.
• Chylothorax: Milky pleural fluid due to lymph; high triglyceride levels (>110 mg/dL).