Interstitial Lung Disease Secondary to Sjogren’s Syndrome and Antisynthetase Syndrome: Converging Disease Trajectories

<i>Background and Objectives</i>: Interstitial lung disease is one of the main causes of mortality in Sjögren's Syndrome (SjS) and Anti-Synthetase Syndrome (ASyS). The objective of the study is to compare clinical, serological and radiological features of these conditions, as well as their prognosis. <i>Materials and Methods</i>: we retrospectively enrolled 34 SjS-ILD and 33 ASyS-ILD patients. The two cohorts were jointly followed by rheumatologists and pulmonologists for at least two years. <i>Results</i>: From a clinical point of view, ASyS-ILD patients showed a greater prevalence of myositis (18.2% vs. 2.3%, <i>p</i> = 0.04), whereas more SjS patients had sicca syndrome (85.3% vs. 9.1%, <i>p</i> < 0.001). No other clinical differences were noted. From a serological point of view, ASyS-ILD patients had a greater proportion of antinuclear antibody positivity with a cytoplasmic pattern (24.9% vs. 2.9%, <i>p</i> = 0.005) and positivity for Anti-Synthetase Antibodies (ASA), which were not found in the SjS cohort. SjS-ILD patients were mainly positive for anti-Ro52kD (61.8% vs. 27.3%, <i>p</i> = 0.002). No significant differences were noted in radiological pattern of ILD, functional values, disease progression and prognosis. <i>Conclusions</i>: SjS-ILD and ASyS patients show several common features. It could be hypothesized that some patients classified as SjS-ILD could have undetectable or unknown ASA, and the upcoming ASyS classification criteria may be useful in highlighting these patients for deeper research.