Interstitial Pneumonia with Autoimmune Features

An estimated 25% of patients with suspected systemic rheumatic disease have symptoms that point to underlying autoimmunity but do not have enough features that result in a clear diagnosis of connective tissue disease (CTD).^1,2 IPAF is a term to identify patients who have idiopathic interstitial pneumonia and features consistent with a CTD but do not fit criteria suggestive of a definitive CTD diagnosis.³

CLASSIFICATION CRITERIA³

Classification criteria for an IPAF diagnosis surrounds the presence of a combination of features from three domains:

CLINICAL DOMAIN³

• Extra-thoracic clinical features
  • Mechanic’s hands
  • Digital tip ulceration
  • Inflammatory arthritis
  • Palmar telangiectasia
  • Raynaud’s phenomenon
  • Digital edema
  • Gottron’s sign

SEROLOGIC DOMAIN³

• Specific autoantibodies including:
  • ANA (Antinuclear antibody)
  • Rheumatoid factor
  • Anti-CCP (cyclic citrullinated peptide)
  • Anti-Ro/La (SS-A)/(SS-B)
  • Anti—ribonucleoprotein
  • Anti-topoisomerase (Scl-70)
  • Anti-tRNA synthetase (e.g. Jo-1, PL-7, PL-12; others)
  • Anti-PM-Scl (polymyositis scleroderma)
  • Anti-MDA-5 (melanoma differentiation-associated protein 5)

MORPHOLOGIC DOMAIN³

• High resolution computed tomography (HRCT), histopathologic, or physiologic pulmonary features
  • HRCT/Histopathology
    • NSIP (non-specific interstitial pneumonia)
    • OP (organizing pneumonia)
    • Non-specific interstitial pneumonia/organizing pneumonia (NSIP/OP)
    • LIP (lymphoid interstitial pneumonia)
• Other Histopathology
• Multicompartment involvement