Etymology

• Derived from the Greek words bronchos, meaning “windpipe,” and ektasis, meaning “expansion,” referring to abnormal and permanent dilation of the bronchi.

AKA

• None significant

What is it?

• Bronchiectasis is a chronic condition characterized by abnormal, permanent dilation of the bronchi due to destruction of the bronchial wall, often accompanied by inflammation and mucus hypersecretion.

Caused by:

• Most common causes:
  • Recurrent or chronic infections (e.g., tuberculosis, nontuberculous mycobacteria)
  • Cystic fibrosis (CF) – the most common cause in children
• Less common causes:
  • Infection:
    • Aspiration pneumonia
    • Fungal infections (e.g., aspergillosis)
  • Inflammation:
    • Autoimmune diseases (e.g., rheumatoid arthritis, Sjögren’s syndrome)
    • Radiation-induced lung injury
    • Traction bronchiectasis associated with interstitial lung diseases (e.g., idiopathic pulmonary fibrosis, sarcoidosis)
  • Immune:
    • Immune deficiency syndromes (e.g., common variable immunodeficiency)
  • Neoplasm:
    • Post-obstructive bronchiectasis due to tumors
  • Mechanical:
    • Post-obstructive processes (e.g., foreign body)
    • Traction bronchiectasis associated with interstitial lung diseases (e.g., idiopathic pulmonary fibrosis, sarcoidosis)
  • Inherited and Congenital:
    • Primary ciliary dyskinesia (e.g., Kartagener syndrome)
    • Alpha-1 antitrypsin deficiency
  • Other:
    • Idiopathic bronchiectasis

Resulting in:

• Chronic productive cough with sputum production
• Recurrent respiratory infections
• Progressive airflow obstruction and hypoxemia

Structural Changes:

• Permanent bronchial dilation with destruction of elastic and muscular components of the bronchial wall
• Mucus plugging and impaired ciliary clearance
• Associated areas of atelectasis or fibrosis

Pathophysiology:

• The cycle of infection and inflammation leads to progressive bronchial wall damage. Repeated insults cause destruction of cilia and the bronchial wall, leading to mucus stasis and further infections. Chronic inflammation exacerbates structural damage, resulting in bronchial dilation.

Pathology:

• Dilated bronchi with thickened walls
• Mucus plugs and inflammation in the bronchial lumen
• Adjacent interstitial fibrosis in advanced cases

Diagnosis

Clinical:

• Chronic productive cough with purulent sputum
• Hemoptysis in severe cases
• Recurrent episodes of bronchitis or pneumonia
• Breathlessness and fatigue

Radiology:

• CXR:
  • Tram-track opacities (parallel bronchial walls)
  • Ring shadows representing dilated bronchi on cross-section
• CT of the Chest:
  • Bronchial dilation with a diameter larger than accompanying pulmonary arteries (signet ring sign)
  • Lack of bronchial tapering
  • Thickened bronchial walls and mucus plugging
  • Associated findings like atelectasis or air trapping

Labs:

• Sputum cultures to identify infective organisms
• Sweat chloride test for cystic fibrosis
• Immunoglobulin levels for immune deficiencies

Management:

• Antibiotics for acute infections
• Airway clearance techniques (e.g., chest physiotherapy, mucolytics)
• Bronchodilators for associated airway obstruction
• Address underlying causes (e.g., immunoglobulin replacement, anti-inflammatory treatments)
• Surgical resection in localized, refractory cases

Radiology Detail

CXR

Findings:

• Tram-track opacities and ring shadows
• Areas of consolidation in superimposed infection

Associated Findings:

• Hyperinflation or volume loss in affected regions
• Atelectasis or adjacent fibrosis

CT of the Chest

Parts:

• Segmental and subsegmental bronchi, predominantly in lower lobes

Size:

• Dilated bronchi, exceeding the size of accompanying pulmonary arteries
• Normally, the ratio of bronchus to artery diameter is approximately 1:1; a larger ratio suggests bronchiectasis
• The “signet ring sign” is a key indicator where the bronchus is larger than the adjacent artery.

Shape:

• Cylindrical, varicose, or saccular bronchial dilation

Position:

• Often affects the lower lobes but may involve any region
• Upper lobe involvement is common in cystic fibrosis

Character:

• Thickened bronchial walls with or without mucus plugging
• Associated air trapping in expiratory images

Time:

• Chronic and progressive

Associated Findings:

• Mucus plugs, atelectasis, air trapping, or consolidation

Other relevant Imaging Modalities

MRI/PET CT/NM/US/Angio:

• MRI: Rarely used but may help in characterizing soft tissue abnormalities
• PET-CT: Useful in identifying infection or malignancy in atypical cases

Pulmonary Function Tests (PFTs):

• May show obstructive or mixed obstructive-restrictive patterns

Recommendations:

• CT of the Chest for definitive diagnosis
• Sputum analysis for microbial identification and tailored antibiotic therapy
• Early diagnosis and management of underlying causes to prevent progression

Key Points and Pearls:

• Bronchiectasis is a chronic, progressive disease resulting from recurrent infections and inflammation.
• CT of the Chest is the gold standard for identifying bronchial dilation and associated abnormalities.
• Early identification and management of underlying conditions are crucial for preventing further lung damage.
• Airway clearance and infection control are central to treatment strategies.