Table 1.

Main serum markers, clinical features and radiological patterns of autoimmune lung CTDs

CTD	Serum markers	Clinical features	HRCT features
RA	Anti-CCP, RF	Erosive and symmetric inflammatory arthropathy, subcutaneous nodules, skin ulceration Lung involvement: exertional dyspnea non-productive cough, bibasilar inspiratory crackles (edema, cyanosis and signs of pulmonary hypertension)	UIP, NSIP patterns Airway disease with obliterative and follicular bronchiolitis Rheumatoid nodules
SSc	ACA Anti-Scl70, anti-RNA polymerase III	Skin thickening, telangiectasias, fingertip ulcers, gastrointestinal diseases, myocardial diseases Lung involvement: exertional dyspnoea, non-productive cough fatigue, “velcro” crackles	NSIP pattern, UIP pattern with straight-edge sign and/or “Four Corners” sign PH
IIM	Increased CK levels; positivity for MSAs/MAAs	Muscle weakness, systemic involvement and specific cutaneous manifestations (for DM heliotrope rash and Gottron papules) Lung involvement: (a) rapidly progressive dyspnea and respiratory failure. (b) insidious onset of dyspnoea	Hypoventilation and respiratory failure due to respiratory muscles involvement; aspiration pneumonia NSIP or OP pattern
SLE	ANA Anti dsDNA antibodies; anti-Sm; lupus anticoagulant Ro/SSA antibodies; hypocomplementemia	Rheumatological, dermatological and renal abnormalities Lung involvement: acute symptoms (dyspnoea, respiratory failure)—in cases of hemorrhage of ALP; dyspnea and cough in interstitial pneumonitis	Pleuritis, pleural effusions, pulmonary infections, chronic interstitial lung diseases (with NSIP pattern), ALP, DAH
pSS	ANA, anti-Ro60kD; anti-Ro52kD; anti-La	Xerostomia and xerophthalmia, focal lymphocytic sialadenitis Lung involvement: it could be asymptomatic In symptomatic cases, cough and dyspnea are often present	NSIP pattern LIP with diffuse interstitial and peribronchiolar infiltration of lymphoplasma cells OP pattern
MCTD	Anti-U1 RNP, anti-Ro52 antibodies	Patients are often asymptomatic Dysphagia and RP, diffuse hand edema (puffy hands)	NSIP, UIP; OP and DAD have been occasionally described

ACA, anticentromere antibodies; IIM, idiopathic inflammatory myopathy; ANA, antinuclear antibodies; MCTD, mixed connective tissue disease; MAA, myositis associated antibodies; MSAs, myositis specific antibodies; pSS, Primary Sjӧgren’s Syndrome; RA, rheumatoid arthritis; RF, rheumatoid factor; SLE, systemic lupus erythematosus; IIM, The term idiopathic inflammatory myopathy includes polymyositis, dermatomyositis, antisynthetase syndrome; MAA, this group of antibodies includes anti-Ro52kD, anti Pm/Scl 100 and 75Kd, anti-Ku, anti-RNP; MSA, this group of antibodies includes antisynthetase antibodies (anti-Jo1, PL7, PL12, EJ, OJ, Ks), anti-Mi2, anti SAE, anti-MDA5