Connective tissue diseases affecting the lung

• Connective tissue diseases (CTDs) = systemic autoimmune disorders
  – e.g. RA (rheumatoid arthritis), SLE (systemic lupus erythematosus), sarcoidosis

• Lung involvement is common and may affect:

  • Airways (bronchiolitis, bronchiectasis)

  • Interstitium (interstitial lung disease, ILD)

  • Pleura (pleuritis, effusions)

  • Pulmonary vasculature (pulmonary hypertension, PE)

• Pulmonary disease is a major cause of morbidity & mortality in CTDs → early recognition in primary care is key.

General patterns of CTD lung disease

CTD-related lung disease usually falls into three main patterns:
1️⃣ Interstitial lung disease (ILD) – most often NSIP or UIP; NSIP = mainly inflammatory (ground-glass, better prognosis), UIP = fibrotic (reticulation/honeycombing, worse prognosis).
2️⃣ Pleural disease – pleuritis, effusions or pleural thickening, especially in RA and SLE.
3️⃣ Pulmonary hypertension (PH/PAH) – important vascular complication, particularly in systemic sclerosis.

Lung involvement may precede, coincide with, or follow systemic CTD features. Screening is not standardised, but a stepwise approach using PFTs, HRCT, and assessment for PH/PAH (e.g. echocardiography) is recommended in patients with CTD or suspected CTD.