Download A4Medicine Mobile App

Empower Your RCGP AKT Journey: Master the MCQs with Us!

Try Now!
A4Medicine
0

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.



Pattern 🫁 Typical CTDs & Prevalence Key Clinical Features (PC setting) Typical Ix (investigations) Notes / Prognosis
Interstitial lung disease (ILD) Seen across most CTDs; overall ≈15% of CTD pts develop CTD–ILD over disease course • Exertional dyspnoea ± dry cough
• May be asymptomatic – found on CXR/CT for other reasons
• Fine “velcro” basal inspiratory crackles on exam 		• HRCT chest: reticular / ground-glass ± honeycombing in advanced fibrosis
• PFTs: restrictive pattern, ↓DLCO 		• Most common parenchymal manifestation
• Can progress from mild change → progressive pulmonary fibrosis if missed / late referral
Pleural disease (pleuritis, effusion, thickening) Especially RA & SLE
• RA: pleural involvement at autopsy in up to ~40–70%, but clinically overt effusion in only ~2–5% of pts 		• Pleuritic chest pain, SOB, dry cough
• May be incidental effusion on CXR
• Recurrent / unexplained exudative effusion in known or suspected CTD 		• CXR/US: unilateral or bilateral effusion
• Pleural fluid: typically exudate, ↑protein, mixed cells
• RF in pleural fluid ≥ serum suggests RA; in SLE, consider other causes (PE, renal, cardiac) 		• In SLE, “serositis” is common but pleural disease may have multifactorial causes → broad ddx
• Usually treatable but may signal active systemic disease
Pulmonary hypertension (PH) Overall ≈13% of CTD pts; particularly systemic sclerosis (SSc) (≈8–12% develop PAH) • Often insidious: exertional dyspnoea, fatigue, ↓exercise tolerance, presyncope/syncope
• May have loud P2, TR murmur, peripheral oedema 		• Echo screening in high-risk CTDs (esp. SSc)
• Confirm with R heart catheterisation in specialist care 		• Mechanisms: CTD-PAH, PH due to ILD, LV dysfunction, rare PVOD
• Prognosis worse than idiopathic PAH – 1-yr survival ~86% vs 93% in idiopathic PAH
• Early recognition & specialist referral essential


Rheumatoid arthritis (RA) – lung points for primary care

  • How common?

    • RA affects ~1% of adults; lungs = most common extra-articular site.

    • Up to ~60% develop some pulmonary manifestation over time; RA-ILD is a major cause of death and can precede joint symptoms.

  • What lung patterns?

    • Can affect all compartments:

      • Parenchyma: ILD, rheumatoid nodules

      • Pleura: pleuritis/effusion

      • Airways: bronchiolitis, bronchiectasis, cricoarytenoid arthritis

      • Vessels: vasculitis, PH

    • ILD patterns on HRCT:

      • UIP → fibrotic, worse prognosis (↑mortality)

      • NSIP → more inflammatory, better outcome

  • Drug issues / what GPs should remember

    • Most RA-ILD pts are seropositive (RF / anti-CCP/ACPA).

    • Methotrexate & other DMARDs:

      • Need baseline CXR (± HRCT if ILD suspected) and monitoring for new cough/SOB.

      • Consider drug-induced pneumonitis vs progression of RA-ILD.

    • Action: new or worsening breathlessness/cough or “velcro” crackles in RA → early resp/rheum referral.


Systemic lupus erythematosus (SLE) – lung points for primary care

  • How common?

    • Pulmonary involvement in 50–70% of SLE pts; 4–5% present with lung disease first.

    • ↑ pulmonary risk with anti-dsDNA and complement-fixing antibodies.

  • Key pulmonary/pleural problems (8 “big ones” to remember):

    • Pleuritis & pleural effusion (part of classification criteria)

    • Acute lupus pneumonitis

    • ILD

    • Diffuse alveolar haemorrhage (DAH) – high mortality, think if dyspnoea + haemoptysis + ↓Hb

    • Shrinking lung syndrome (uncommon)

    • Pulmonary arterial hypertension (PAH)

    • Pulmonary embolism / thromboembolism

  • What GPs should do

    • Take new dyspnoea, pleuritic chest pain, haemoptysis, or persistent cough in SLE very seriously.

    • First-line tests: CXR (± HRCT, PFTs, D-dimer, echo, depending on concern).

    • Suspected DAH, PE, or acute pneumonitis → urgent ED/hospital.

    • Treatment usually with immunosuppression (steroids, cyclophosphamide, ± rituximab) – specialist-led.


Sarcoidosis – lung points for primary care

  • What it is / how common in chest?

    • Multisystem granulomatous disease (not a classic CTD, but overlaps with autoimmunity).

    • >90% have intrathoracic involvement (lungs + hilar/mediastinal nodes).

    • Can coexist (rarely) with RA or SLE.

  • Typical presentation

    • Often asymptomatic (esp. Stage I).

    • Symptoms: dry cough, dyspnoea, chest tightness, sometimes systemic features (fatigue, weight loss).

    • CXR:

      • Stage I – bilateral hilar lymphadenopathy (BHL) only

      • Stage II – BHL + parenchymal infiltrates

      • Stage III – infiltrates only

      • Stage IV – fibrosis

    • Diagnosis needs compatible clinical picture + non-caseating granulomas on biopsy and exclusion of other causes (TB, lymphoma, etc.).

  • Prognosis & when to refer

    • Stage I often resolves spontaneously.

    • Stage III–IV → ↑ risk (≈5-fold) of chronic respiratory impairment.

    • Treatment (usually for symptomatic or progressive disease):

      • Oral steroids first-line; steroid-sparing agents/biologics if refractory – specialist-driven.

    • GP role: monitor respiratory symptoms, arrange baseline CXR/PFTs, and refer if persistent symptoms, falling lung function, or advanced radiographic stage.


Take-home points for primary care

  • Think lung early in CTD
    Any cough, dyspnoea or pleuritic chest pain in RA, SLE or sarcoidosis → investigate, don’t just label as infection/anxiety/asthma.


  • Baseline & monitoring tests

    • Arrange baseline + interval PFTs (↓DLCO can be an early clue).

    • HRCT if symptoms, abnormal PFTs, or “velcro” crackles → to pick up subclinical ILD.


  • Lung-first presentations happen

    • RA-ILD, SLE pleuro-pulmonary disease and sarcoidosis can precede classic joint/skin/systemic features.

    • Unexplained ILD / hilar lymphadenopathy → consider underlying CTD and refer.


  • Treat the systemic disease & watch the drugs

    • Aggressive RA/SLE control helps limit lung damage.

    • Monitor for drug toxicity, especially methotrexate-related pneumonitis or other DMARD/biologic lung effects.


  • Shared care with specialists

    • Early and ongoing rheumatology/respiratory input for ILD, PH, DAH or progressive sarcoidosis.

    • GP role: optimise vaccinations (influenza, pneumococcal, COVID), support smoking cessation, and maintain high vigilance for infection.


  • Bottom line
    This summary is to help GPs spot lung involvement early, start appropriate first-line investigations, and refer promptly to protect long-term respiratory function.


References

  1. Pulmonary sarcoidosis complicated by rheumatoid arthritis: case report and literature review. 2023. PMC9989416.

  2. Connective Tissue-Related Interstitial Lung Disease Primer. ATS Educational Resource. American Thoracic Society; 2020. thoracic.org.

  3. SLE Linked to Increased Risk for Pulmonary Manifestations. Rheumatology Advisor; 2025.

  4. Treatment of connective tissue disease-associated interstitial lung disease. 2017. PMC5511941.

  5. Pulmonary Manifestations of Systemic Lupus Erythematosus. 2024. PMC10949994.

  6. Pulmonary Manifestations of Connective Tissue Diseases. 2021. NCBI Bookshelf.

  7. Management of interstitial lung disease associated with connective tissue disease. BMJ.

  8. Screening for Pulmonary Hypertension in Connective Tissue Disease. Anatolian Journal of Cardiology; 2025.

  9. Rheumatoid arthritis presenting with bilateral pleural involvement (case report). mansapublishers.com.

  10. Prevalence of pulmonary arterial hypertension in patients with connective tissue disease. 2013. PMC3778216.

  11. The benefits of a rapid diagnostic primary care circuit for early detection of interstitial lung disease. Nature; 2025.

  12. Connective tissue disease-associated pulmonary hypertension: A comprehensive review. 2023. PMC10711418.

  13. Multidisciplinary Approach in the Early Detection of Connective Tissue Disease-Associated Interstitial Lung Disease. Frontiers in Medicine; 2020.

  14. Pulmonary hypertension in connective tissue diseases, new evidence and challenges. 2020. PMC7988614.

  15. Connective tissue disease-associated pulmonary hypertension: A comprehensive review. Wiley Online Library.