What are the lobe-specific causes of bronchiectasis?

Lobe-Specific Causes of Bronchiectasis

Bronchiectasis has distinct lobe-specific patterns that can help identify the underlying etiology, with certain conditions predominantly affecting specific lobes of the lungs. 1, 2

Upper Lobe Predominant Bronchiectasis

• Cystic Fibrosis (CF): Typically affects upper lobes first

  • Occurs in 3-4% of adult bronchiectasis patients 1
  • Requires sweat chloride testing and genetic analysis for confirmation
  • Associated with Staphylococcus aureus colonization 1

• Post-tuberculosis: Scarring and fibrosis following TB infection

  • Predominantly affects posterior segments of upper lobes
  • Often associated with volume loss and fibrotic changes

• Sarcoidosis: Granulomatous inflammation leading to traction bronchiectasis

  • Upper lobe predominance with peribronchial thickening

Middle Lobe and Lingula Predominant Bronchiectasis

• Non-tuberculous Mycobacterial (NTM) Infection: Particularly MAC (Mycobacterium avium complex)

  • Classic "Lady Windermere syndrome" affecting elderly women 1
  • Presents with chronic cough, fever, and weight loss
  • Characteristic nodular bronchiectasis in middle lobe and lingula 1
  • Often shows tree-in-bud pattern on CT imaging

• Allergic Bronchopulmonary Aspergillosis (ABPA):

  • Affects central bronchi (inner two-thirds of chest on CT)
  • Found in 4% (range 1-8%) of bronchiectasis patients 1
  • Diagnostic criteria include:
    • Central bronchiectasis
    • Elevated total IgE (>500 IU/mL)
    • Positive Aspergillus-specific IgE or skin test 1
    • Often associated with mucoid impaction 1

Lower Lobe Predominant Bronchiectasis

• Primary Ciliary Dyskinesia (PCD):

  • Predominantly affects lower lobes
  • Found in ≤5% of adult bronchiectasis patients 1
  • Associated with situs inversus in Kartagener syndrome
  • Haemophilus influenzae is the most common bacterial isolate, but Pseudomonas is also common 1

• Immunodeficiency Disorders:

  • Antibody deficiency syndromes (7% of bronchiectasis cases) 1
  • Hypogammaglobulinemia
  • Specific antibody deficiency against pneumococcal polysaccharides
  • Typically affects bilateral lower lobes

• Aspiration-related Bronchiectasis:

  • Predominantly affects dependent portions (posterior segments of lower lobes)
  • Often associated with gastroesophageal reflux disease 1
  • May be seen with neurological disorders affecting swallowing

Diffuse Bronchiectasis (Multiple Lobes)

• Rheumatoid Arthritis:

  • Up to 3% of RA patients have symptomatic bronchiectasis 1
  • Up to 30% have CT-diagnosed disease
  • Often affects multiple lobes

• Inflammatory Bowel Disease:

  • Particularly ulcerative colitis
  • Associated with recurrent respiratory infections 1
  • Usually diffuse distribution

• Alpha-1 Antitrypsin Deficiency:

  • Found in <1% of bronchiectasis patients 1
  • Often associated with emphysema

Localized Bronchiectasis (Single Lobe/Segment)

• Foreign Body Aspiration:

  • Affects the lobe distal to obstruction
  • More common in right bronchial tree due to anatomical factors

• Endobronchial Tumors:

  • Cause obstruction leading to post-obstructive bronchiectasis
  • Location depends on tumor site

• Congenital Abnormalities:

  • Williams Campbell syndrome (bronchomalacia)
  • Mounier Kuhn syndrome (tracheobronchomegaly)
  • Lung sequestration 1

Clinical Approach

1. High-resolution CT is essential for diagnosis and determining distribution pattern 2
2. Investigate for underlying causes based on distribution pattern
3. Consider specific testing based on lobe involvement:
   • Upper lobe: CF testing, TB screening
   • Middle lobe/lingula: NTM cultures, Aspergillus testing
   • Lower lobe: Immunoglobulin levels, ciliary function tests
   • Diffuse: Autoimmune markers, alpha-1 antitrypsin

Pitfalls and Caveats

• Distribution patterns may overlap and are not always definitive for diagnosis
• Multiple etiologies may coexist in the same patient
• Idiopathic bronchiectasis remains common despite thorough investigation
• Chronic colonization with certain organisms (e.g., Pseudomonas aeruginosa) can worsen disease progression regardless of initial cause
• Traction bronchiectasis due to surrounding fibrosis may complicate the interpretation of distribution patterns

Understanding lobe-specific patterns helps guide diagnostic workup and may lead to specific treatments that can slow or halt disease progression 2.