Ankylosing Spondylitis


  • Prevalence: affects 0.05-1.5% of the population
  • Age: usually occurs in <40 y/o’s
  • Sex: M:F ratio is 10:1
    • Females tend to have milder and more peripheral disease with fewer radiographic changes in spine
  • Race: rare in non-whites
  • Genetic Factors: >90% of whites with ankylosing spondylitis are HLA-B27 positive


  • Immunologic Mechanism
  • Cardinal Site of Disease: vertebral column -> leads to development of fibrosis and ossification -> eventual ankylosis of vertebral joints
  • Decreased Ventilation to Lung Apices: may predispose changes that develop in this area


  • Spine X-Rays: bilateral sacroiliitis

Clinical Manifestations

Cardiovascular Manifestations

Ophthalmologic Manifestations

Pulmonary Manifestations (typically insidious onset)

Apical Interstitial Lung Disease with or without Apical Fibrobullous Disease

  • Epidemiology
    • Apical interstitial lung disease is the most common pattern of lung involvement: 30% of cases have upper zone fibrosis
      • Fibrobullous changes are less common, being seen in 1-2% of cases
      • Apical interstitial changes usually progress to fibrobullous changes over time
    • Although usually occurs in long-standing ankylosing spondylitis cases, subclinical pulmonary involvement is common early in the course of the disese
  • Diagnosis
    • CXR/Chest CT: apical reticulonodular infiltrates or fibrobullous changes (often mimicking those seen in TB): usually bilateral
      • Apices may be secondarily infected or retracted
    • FOB: subclinical lymphocytic alveolitis may be seen
    • Open Lung Biopsy
      • Pneumonic-like process: patchy round cell or fibroblastic infiltration progressing to extensive fibrosis
      • Dense pleural fibrosis is usually associated with parenchymal fibrosis
      • Bronchiectasis: may be seen
      • Bullous changes may be seen
  • Clinical
    Asymptomatic or may present with cough, sputum, dyspnea, absence of clubbing

    • Pulmonary Superinfection (with TB, atypical mycobacteria, or Aspergillus fumigatus): may complicate the apical fibrobullous changes
      • Aspergillus fumigatus is isolated from 60% of cases with apical cavitation
    • Hemoptysis: may result from apical cavitary disease
  • Treatment
    • No treatment has been proven to prevent apical fibrosis: it is typically resistant to corticosteroid therapy
    • Bronchial artery embolization: may be necessary to control hemoptysis
    • Avoid surgial resection of Aspergilloma unless bleeding is refractory: due to high risk of post-op bronchopleural fistula and empyema

Pleural Disease

  • Clinical
    • Apical Pleural Thickening: early finding in ankylosing spondylitis
    • Pleural Calcifications
    • Pleural Effusion (see Pleural Effusion-Exudate, [[Pleural Effusion-Exudate]]): rare
      • Usually exudate with normal glucose (but empyema has been reported)
    • Pleuritis

Spontaneous Pneumothorax (see Pneumothorax, [[Pneumothorax]])

  • Physiology: may occur due to rupture of apical bullae

Atelectasis (see Atelectasis, [[Atelectasis]])

  • xxx

Chronic Aspiration Pneumonia (see Aspiration Pneumonia, [[Aspiration Pneumonia]]):

  • xxx

Thoracic Cage Immobility

  • Physiology: costovertebral spondylosis (which may occur in advanced cases)
  • Diagnosis
    • ABG: minimal gas exchange abnormalities
    • PFT’s: fixation of thorax at high volume and decreased chest wall compliance (although ankylosing spondylitis generally does not usually lead to significant pulmonary dysfunction)
      • Expiratory flow rates: normal
      • TLC (and VC): slight-moderate decrease
      • FRC and RV: normal-slightly increased
  • Clinical

Bronchocentric Granulomatosis (see Bronchocentric Granulomatosis, [[Bronchocentric Granulomatosis]])

  • xxx

Scar Lung Carcinoma (see Lung Cancer, [[Lung Cancer]])

  • Clinical
    • Adenocarcinoma
    • Squamous Cell Carcinoma

Mediastinal Fibrosis (see xxxx, [[xxxx]])

  • xxx

Cricoarytenoid Arthritis (see Cricoarytenoid Arthritis, [[Cricoarytenoid Arthritis]]): has been reported

  • Clinical
    • Upper Airway Obstruction
    • Acute Respiratory Failure
    • Cor Pulmonale

Renal Manifestations

  • Chronic Prostatism

Rheumatologic Manifestations

  • Arthritis of Peripheral Joints (see Arthritis, [[Arthritis]]): 33% of cases
  • Atlantoaxial Instability (see Atlantoaxial Instability, [[Atlantoaxial Instability]])
  • Spine Arthritis (see Arthritis, [[Arthritis]]): back pain and morning stiffness (that improves with exercise) are common

Other Manifestations

  • Fatigue (see Fatigue, [[Fatigue]])
  • Low-Grade Fever (see Fever, [[Fever]])
  • Weight Loss (see Weight Loss, [[Weight Loss]])


  • Corticosteroids (see Corticosteroids, [[Corticosteroids]])
    • Pulmonary apical fibrotic changes are typically steroid-resistant


  • Pulmonary involvement in ankylosing spondylitis. Ann Rheum Dis. 1986 September; 45(9): 736–740
  • Lung findings on high-resolution computed tomography in idiopathic ankylosing spondylitis–correlation with clinical findings, pulmonary function testing and plain radiography. Rheumatology (1997) 36 (6): 677-682