Idiopathic interstitial lung disease with anti-SSA antibody.

Objectives: Consensus is lacking on the immunological tests to perform for diagnosis of interstitial lung diseases (ILDs). In particular, the value of detecting anti-SSA antibody in this context is unknown. We aimed to determine whether the detection of anti-SSA antibody in patients with ILD can identify a subgroup of patients with CTD.
Methods: We compared the characteristics of patients with newly diagnosed apparently idiopathic ILD with anti-SSA antibody [anti-SSA(+) group] and without anti-SSA antibody (control group). RESULTS; Anti-SSA(+) patients (n = 15) more often had extra-respiratory signs (xerostomia and ocular dryness), auto-immune features, a CT scan pattern of non-specific interstitial pneumonia and more severe lung function alteration than controls (n = 30). Of patients who were anti-SSA(+), 2 met the criteria for SS and 13 (86%) of 15 met the criteria for the diagnosis of undifferentiated CTD.
Conclusions: Our results suggest that identification of anti-SSA antibody in patients with early ILD can reveal a specific subgroup of patients with more ground glass opacity and more severe lung function impairment than those without anti-SSA antibody.