Pleural Irregularities: A new ultrasound marker for lung involvement in primary Sjögren's disease

Lung ultrasound (LUS) has been proposed as a useful tool for the assessment of interstitial lung disease (ILD) in connective tissue diseases. However, there are no studies investigating the significance of pleural irregularities (PI) on LUS in primary Sjögren's disease (SjD) patients. The aim of this study was to explore the role of PI for the assessment of SjD-related lung involvement.

All primary SjD patients who had undergone a chest CT-scan in the lasts 2 months from the start of the study were enrolled, including both SjD patients with known ILD and SjD patients without known lung involvement who underwent a chest CT due to clinical indications other than ILD screening. LUS was performed for all patients and PI total and partial scores were assigned from 0 (normal) to 2 (major changes). Based on CT-scans results SjD patients were divided into 5 groups: normal CT-scan, non SjD-related lung abnormalities, SjD-related non-ILD lung abnormalities, established ILD, newly diagnosed ILD.

Nineteen SjD patients with established ILD and 42 without known lung involvement who had undergone a CT-scan were included. Among the latter, CT allowed the diagnosis of 4 new ILD cases. Both total and postero-inferior PI scores were comparable between established ILD and newly diagnosed ILD patients and significantly higher compared to patients with normal CT-scan and SjD related non-ILD lung abnormalities. The AUC for ILD diagnosis was significantly higher for the PI postero-inferior score compared to the PI total score. A cut-off score of 15 for the PI postero-inferior score resulted in a sensitivity of 86.6% and specificity of 84.2% for SjD-ILD diagnosis. Both PI total and postero-inferior scores strongly correlated with HRCT Warrick score (r=0.809 and r=0.854). The correlation between PFT and both total and postero-inferior PI scores was higher than that observed between PFT and the Warrick HRCT score.

PI may represent a valid tool for the assessment of lung involvement in SjD, particularly for the screening of ILD. PI assessment limited to postero-inferior lung fields seem to maintain good diagnostic accuracy, allowing to save time in clinical practice.