• • Etymology

    • Derived from the Latin words obliterare, meaning “to erase,” and the Greek words bronchion, meaning “small airway,” and -itis, meaning “inflammation.” The term refers to inflammation and scarring of the bronchioles leading to their obliteration.

    AKA

    • Constrictive bronchiolitis
    • Bronchiolitis obliterans

    What is it?

    • Obliterative bronchiolitis is a chronic inflammatory and fibrotic condition characterized by progressive narrowing and obliteration of the bronchioles due to inflammation, fibrosis, and scarring.

    Caused by:

    • Most common causes:
      • Post-transplant complications (e.g., lung, bone marrow, or hematopoietic stem cell transplants)
      • Inhalational injuries (e.g., toxic fumes, gases)
    • Less common causes:
      • Infection:
        • Adenovirus, Mycoplasma pneumoniae, or post-viral bronchiolitis
      • Inflammation:
        • Autoimmune diseases (e.g., rheumatoid arthritis, inflammatory bowel disease)
      • Immune:
        • Chronic rejection in organ transplantation
      • Trauma:
        • Inhalational exposure to irritants (e.g., chlorine, ammonia)
      • Other:
        • Idiopathic obliterative bronchiolitis

    Resulting in:

    • Airflow limitation and obstructive pulmonary dysfunction
    • Progressive dyspnea and hypoxemia
    • Severe ventilation-perfusion mismatch

    Structural Changes:

    • Submucosal fibrosis and inflammation within bronchioles
    • Obliteration of bronchiolar lumens
    • Collateral air trapping and hyperinflation

    Pathophysiology:

    • Obliterative bronchiolitis begins with inflammation of the bronchioles due to infectious, toxic, or immune-mediated insults. Chronic injury leads to fibrotic remodeling, luminal narrowing, and eventual obliteration of the airways. This results in distal air trapping, hypoxia, and progressive respiratory dysfunction.

    Pathology:

    • Submucosal and peribronchiolar fibrosis
    • Luminal narrowing and obliteration of bronchioles
    • Chronic inflammatory infiltrates

    Diagnosis

    Clinical:

    • Symptoms include:
      • Progressive dyspnea
      • Chronic cough
      • Wheezing (in some cases)
    • History of prior transplant, toxic inhalational exposure, or viral infection

    Radiology:

    • CXR:
      • Hyperinflation and small airway opacities
      • Flattening of the diaphragm
    • CT of the Chest:
      • Mosaic attenuation and air trapping on expiratory imaging
      • Bronchial wall thickening
      • Subsegmental atelectasis

    Labs:

    • Autoimmune screening if connective tissue disease is suspected
    • Viral serologies or cultures in post-infectious cases

    Management:

    • Supportive care:
      • Oxygen therapy for hypoxemia
      • Pulmonary rehabilitation
      • Bronchodilators for symptomatic relief
    • Targeted therapy:
      • Corticosteroids and immunosuppressive agents for autoimmune or post-transplant causes
      • Antiviral therapy in post-viral cases if indicated
    • Advanced interventions:
      • Lung transplantation in end-stage disease

    Radiology Detail

    CXR

    Findings:

    • Hyperinflation with flattening of the diaphragm
    • Subtle reticular or nodular patterns

    Associated Findings:

    • Peribronchial thickening
    • Atelectasis in advanced cases

    CT of the Chest

    Parts:

    • Terminal and respiratory bronchioles

    Size:

    • Subtle thickening of small airways

    Shape:

    • Irregular, constricted lumens with mosaic attenuation

    Position:

    • Diffuse distribution, typically affecting lower lung zones

    Character:

    • Mosaic attenuation and air trapping

    Time:

    • Chronic progression with acute exacerbations

    Associated Findings:

    • Evidence of air trapping on expiratory imaging
    • Fibrotic bands or subsegmental atelectasis

    Other relevant Imaging Modalities

    MRI/PET CT/NM/US/Angio:

    • MRI: Rarely used but may identify associated soft tissue changes
    • PET-CT: Useful in assessing inflammation or post-transplant complications

    Pulmonary Function Tests (PFTs):

    • Obstructive pattern with decreased FEV1/FVC ratio
    • Air trapping and hyperinflation

    Recommendations:

    • High-resolution CT for detailed evaluation of small airway disease
    • Biopsy for definitive diagnosis in uncertain cases
    • Early referral to pulmonology or transplant specialists for management

    Key Points and Pearls:

    • Obliterative bronchiolitis is commonly associated with post-transplant rejection and inhalational injuries.
    • High-resolution CT findings include mosaic attenuation and air trapping.
    • Management focuses on supportive care and addressing the underlying cause, with lung transplantation being a final option in severe cases.
    • Early diagnosis and intervention are critical to improving outcomes.

Obliterative Bronchiolitis aka (bronchiolitis obliterans is also known and constrictive bronchiolitis) association to lung transplant and bone marrow  transplant

 

CT Scleroderma Obliterative Bronchiolitis vs 

References and Links

TCV