Cavitating Nodules

• What is it:
  • Cavitating nodules refer to
    • pulmonary nodules that contain a
    • necrosis or gas-filled spaces within
    • surrounding wall of lung parenchyma.
  • These are visible on imaging and are
  • indicative of various
    • infectious, neoplastic, or inflammatory processes.
• Etymology:
  Derived from the Latin word cavus, meaning “hollow,” referring to the central cavity within the nodule.
• AKA:
  Cavitary nodules, Cavitated pulmonary nodules.
• How does it appear on each relevant imaging modality:
  • Chest X-ray:
    • Round or oval nodules with a central lucency surrounded by a dense wall.
    • The wall thickness and size of the cavity may vary.
  • Chest CT:
    • Parts: A nodule with a central cavity surrounded by a rim of lung parenchyma.
    • Size:
      • Typically >10 mm, but
      • may range from
        • small micronodules to
        • larger masses with cavitation.
    • Shape: Usually round or oval.
    • Position: Can be
      • solitary or
      • multip
        • randomly or in
        • specific distributions (e.g., upper lobes in TB).
    • Character:
      • Wall thickness varies:
        • Thick walls (>15 mm) suggest malignancy.
        • Thin walls (<4 mm) suggest
          • benign processes like abscesses.
  • PET-CT:
    • Can help distinguish malignant cavitating nodules from benign causes based on metabolic activity.
• Differential diagnosis:
  • Infection:
    • Bacterial (e.g., Staphylococcus aureus, Klebsiella pneumoniae).
    • Fungal (e.g., aspergillosis, histoplasmosis).
    • Tuberculosis (reactivation TB).
    • Septic emboli (often multiple cavitating nodules).
  • Neoplasm:
    • Primary lung cancer
      • squamous cell carcinoma – most common but
      • adenocarcinoma can also cavitate.
    • Metastatic cancer (e.g., squamous cell metastases, sarcomas).
  • Immune-related or inflammatory:
    • Granulomatosis with polyangiitis (GPA).
    • Rheumatoid nodules (associated with rheumatoid arthritis).
  • Circulatory:
    • Pulmonary infarction with secondary infection or necrosis.
    • Septic emboli (e.g., in IV drug users).
  • Inhalational exposure:
    • Pneumoconiosis (e.g., silicosis with secondary TB or necrosis).
  • Iatrogenic:
    • Post-radiotherapy changes.
  • Trauma:
    • Pulmonary contusion or hematoma (may cavitate if infected).
  • Congenital or inherited:
    • Bronchogenic cysts (cavitating after infection).
  • Metabolic or infiltrative:
    • Pulmonary amyloidosis (rarely cavitating in nodular form).
• Recommendations:
  • Assess clinical history and risk factors (e.g., IV drug use, smoking, immune status).
  • Imaging evaluation:
    • CT chest with contrast to assess wall thickness, nodular size, and associated findings.
    • PET-CT for metabolic activity in nodules to differentiate benign from malignant causes.
  • Perform microbiological workup for suspected infections (e.g., sputum cultures, blood cultures).
  • Biopsy or surgical resection may be required for diagnosis if malignancy or inflammatory causes are suspected.
• Key points and pearls:
  • Wall thickness is critical:
    • Thick-walled cavities (>15 mm) are more likely malignant.
    • Thin-walled cavities (<4 mm) are often benign (e.g., infectious abscess).
  • Septic emboli: Consider in patients with multiple cavitating nodules and IV drug use.
  • Upper lobe predominance: Common in TB or post-primary infection.
  • Early recognition of cavitating nodules can guide timely diagnosis and intervention for underlying conditions.