Inclusion Criteria:  All patients with pSS fulfilled the 2002 revised version of the European criteria proposed by the American-European Consensus Group Patient with pSS evaluated with pulmonary HRCT and/or PFTs were included in the pSS-ILD group  Exclusion Criteria:  patients with hepatitis C infection, past head and neck radiation treatment, sarcoidosis, acquired immunodeficiency syndrome, pre-existing lymphoma, graft-versushost disease, and use of anticholinergic drugs, IgG4-related disease Patients with other connective tissue diseases (CTD) or other pulmonary diseases were further excluded, including those with pulmonary arterial hypertension, pulmonary infections, tuberculosis, chronic bronchitis, emphysema, asthma, chronic obstructive pulmonary disease, malignancies, pulmonary lesions related with environmental, occupational or medication exposures, or history of smoking