Interstitial lung disease in Sjögren's syndrome: a clinical review

Interstitial lung disease (ILD) is considered the most frequent and serious pulmonary complication in primary Sjögren's syndrome (pSS), with the majority of the studies indicating a prevalence of about 20%, and resulting in significant morbidity and mortality. Although ILD was historically described as a late manifestation of pSS, more recently, a high variability of the time of onset of pSS-ILD has been observed and from 10 to 51% of patients can develop ILD years before the onset of pSS. Lymphocytic interstitial pneumonia is highly typical for SS, but it occurs only in a few cases, while the most common ILD pattern is nonspecific interstitial pneumonia, followed by usual interstitial pneumonia and organising pneumonia. Multidisciplinary discussion can be necessary in pSS cases with ambiguous clinical findings, when differential diagnosis with IIPs might be very difficult. Up to date, available data do not allow to establish an evidence-based treatment strategy in pSS-ILD. Glucocorticoids are empirically used, usually in association to immunosuppressive drugs, such as cyclophosphamide and mycophenolate mofetil. A better understanding of the molecular mechanisms involved in the pathogenesis of pSS should facilitate the development of new therapies. Recently, a trial showed the efficacy of the antifibrotic drug nintedanib in slowing progression of various interstitial lung diseases, including patients with connective tissue diseases. The aims of this review are to describe clinical features, imaging, pathology, together with diagnostic criteria, prognosis and management of pSS-ILD patients.