20th February 2025

Overview of connective tissue disease-associated ILD

Several connective tissue diseases (CTD) have respiratory complications, including systemic sclerosis (SSc), rheumatoid arthritis (RA), polymyositis/dermatomyositis (PM/DM), Sjögren’s syndrome, systemic lupus erythematosus (SLE), ankylosing spondylitis and mixed connective tissue disease. This chapter will briefly describe pulmonary involvement in some of the major rheumatological conditions, particularly focusing on interstitial lung disease.

The majority of these diseases cause lower zone fibrosis with the notable exception being ankylosing spondylitis, which causes upper zone fibrosis.

Symptoms and signs are often those associated with the underlying CTD such as rashes, joint pain, constitutional symptoms, ulcers, synovitis, joint deformity, dysphagia, sclerodactyly (particularly in SSc), dry mucosa (present in Sjögren’s), Gottron’s papules (seen in dermatomyositis), and proximal muscle weakness (for example in inflammatory myopathies).

In addition, respiratory features such as dyspnoea, cough and crackles may be noted.

Bloods should be sent to screen for CTD, including ANA, anti-dsDNA, anti-ribonucleoprotein antibody, anti-smith antibody, anti-Scl-70, anti-Ro, anti-La, rheumatoid factor, anticyclic citrullinated peptide, anti-Jo-1 antibody, creatine kinase, aldolase, ESR, CRP.

Lung function tests in most of these conditions show a restrictive pattern with a low KCO.

HRCT usually shows a non-specific interstitial pneumonia pattern although variation between conditions will apply.

Management is driven by a multidisciplinary team approach. There is a low threshold for starting treatment in the hope of preventing pulmonary fibrosis. In most CTD-associated ILD, the mainstay of treatment is steroids and adjuvant immunosuppressive agents.

See note on nintedanib – this has now been approved as a treatment option for chronic progressive fibrosing interstitial lung diseases.