Table 2. Indicative criteria for which patients may be referred for rheumatologic evaluation

	Features suggesting CTD
Demographics	Female sex Age <50 years
Clinical manifestations	Any patient with extra-thoracic manifestations highly suggestive of CTD:
	Raynaud’s phenomenon, oesophageal hypomotility, inflammatory arthritis of the metacarpophalangeal joints or wrists, digital oedema, symptomatic keratoconjonctivitis sicca
Lung histopathology	All cases of NSIP, LIP or ILD patterns with histopathology features that might suggest CTD:
	Extensive pleuritis, dense perivascular collagen, lymphoid aggregates with germinal centre formation, prominent plasmacytic infiltration
Biology	Patients with positive high-titre antinuclear antibodies (>1:320) or rheumatoid factor (>60 IU·mL⁻¹), nucleolar staining antinuclear antibodies or specific antibodies (anti-cyclic citrullinated peptide, anti-Scl70, anti-Ro, anti-La, anti-dsDNA, anti-Smith, anti-RNP, anti-tRNA synthetase)

CTD: connective tissue disease; NSIP: nonspecific interstitial pneumonia; LIP: lymphoid interstitial pneumonia; ILD: interstitial lung disease; RNP: ribonucleoprotein. Adapted from [37].