• What is it:
    • Endobronchial nodules refer to
    • multiple nodules located
    • within the bronchial tree.
    • often resulting from
      • infectious, inflammatory, or metastatic processes and are
    • distinct from
      • solitary endobronchial neoplasms.
  • Etymology:
    Derived from the Greek word bronchos (windpipe) and the Latin prefix endo- (within), indicating the intraluminal location of these nodules.
  • AKA:
    Multiple intrabronchial nodules.
  • How does it appear on each relevant imaging modality:
    • Chest X-ray:
      • Indirect signs include:
        • Airway obstruction with atelectasis or post-obstructive consolidation.
        • May show branching opacities if nodules are associated with mucus plugging or inflammation.
    • Chest CT:
      • Parts: Multiple nodules within the bronchial lumen, occasionally with associated airway thickening.
      • Size: Nodules range from 1?10 mm; some may exhibit central cavitation.
      • Shape: Round, oval, or irregular, conforming to the airway lumen.
      • Position: Confined to the bronchial lumen; often segmental or lobar distribution.
      • Character:
        • May appear as soft-tissue density (e.g., granulomas or metastatic nodules).
        • Associated with airway inflammation or mucus plugging.
      • Time:
        • Nodules may resolve (e.g., infectious causes) or progress (e.g., metastatic spread or chronic inflammation).
    • Bronchoscopy:
      • Visualizes multiple intrabronchial nodules, typically as polypoid lesions or clustered growths.
      • Allows for sampling to determine the underlying etiology.
    • PET-CT:
      • Useful for evaluating metabolic activity, particularly in suspected metastatic nodules.
  • Differential diagnosis:
    • Infection:
      • Endobronchial spread of tuberculosis.
      • Fungal infections with multiple nodules (e.g., aspergillosis, cryptococcosis).
      • Viral or bacterial infections with debris or granulomas.
    • Inflammation:
      • Allergic bronchopulmonary aspergillosis (ABPA) with mucus and nodular inflammation.
      • Bronchocentric granulomatosis.
    • Neoplasm (secondary):
      • Endobronchial metastases from extrapulmonary malignancies (e.g., renal cell carcinoma, melanoma).
    • Immune-related:
      • Sarcoidosis with endobronchial granulomas.
      • Granulomatosis with polyangiitis (GPA).
    • Iatrogenic:
      • Retained surgical materials causing inflammatory nodules.
    • Congenital or inherited:
      • Bronchial atresia with nodular mucus impaction.
    • Trauma:
      • Granulation tissue secondary to airway injury or instrumentation.
  • Recommendations:
    • Perform high-resolution CT to determine the number, size, and distribution of nodules.
    • Bronchoscopy: Essential for direct visualization and sampling of nodules to determine infectious or malignant causes.
    • Obtain microbiological samples (e.g., sputum, bronchial lavage) for suspected infections.
    • Consider PET-CT to evaluate for metabolically active or malignant lesions.
  • Key points and pearls:
    • Emphasis is on multiple nodules, often caused by infectious or metastatic processes rather than primary airway neoplasms.
    • Secondary endobronchial involvement from metastases or granulomatous diseases is a critical differential.
    • Post-obstructive changes, such as atelectasis or pneumonia, can provide clues to the underlying pathology.
    • Resolution of nodules over time may favor benign or infectious causes, while progression may indicate metastatic disease.