To characterize the distinctive chest high-resolution computerized tomography (HRCT) features and clinical manifestations of primary Sjögren syndrome (pSS)-related interstitial lung disease (ILD). The demographic data, clinical manifestations, and laboratory and radiological findings of 527 pSS patients were retrospectively analyzed. ILD was defined based on the presences of pulmonary signs in HRCT. Two hundred six of 527 patients were diagnosed as pSS-ILD, and the prevalence was 39.1%. The three most frequent abnormalities in HRCT were reticular pattern (92.7%), ground-glass attenuation (87.4%), and bronchovascular bundle thickening (82%). One hundred twenty-four cases (60.2%) of the pSS-ILD patients had only a single HRCT pattern, which involved 86 non-specific interstitial pneumonitis (NSIP) cases (41.7%), 22 usual interstitial pneumonia (UIP) cases (10.68%), 8 organizing pneumonia (OP) cases (3.9%), and 8 lymphocytic interstitial pneumonia (LIP) cases (3.9%), respectively. Besides, the more important observation was that 82 cases had no less than two HRCT patterns, and NSIP admixed with OP (43.9%), NSIP admixed with UIP (35.4%), and NSIP admixed with LIP (19.5%) were the most frequent. HRCT of pSS-ILD patients demonstrated bilateral infiltrates (99%), with abnormalities predominantly in the lower lobes (89.3%) and subpleural areas (81.1%), and a few lesions were characterized by hilum distributed (8.7%). Pulmonary function tests (PFTs) revealed impaired diffusion capacity for carbon monoxide and total lung capacity, and the rate of small airway lesions in the pSS-ILD patients was 3.5 times higher in patients of pSS. Logistic regression analysis showed that dry cough (OR 59.05), clubbing (OR 6.26), elevated lactate dehydrogenase (OR 21.38) and positive anti-Ro (OR 7.86) were relevant factors of pSS-ILD. ILD is the common pulmonary involvement of pSS and the prevalence of pSS-ILD is 39.1%. The single pattern of NSIP and UIP in HRCT are the commonest, and about 40% of the pSS-ILD patients possess multiple patterns in HRCT. The classification of idiopathic pulmonary fibrosis cannot completely include the pulmonary imaging features of pSS-ILD.
Keywords: High-resolution computed tomography; Interstitial lung disease; Primary Sjögren syndrome.