Patterns of Interstitial Lung Disease in Egyptian Patients with Systemic Sclerosis: Relation to Disease Parameters

Background: Pulmonary involvement is the most common leading cause of morbidity and mortality associated with systemic sclerosis. Therefore, identifying the various patterns of pulmonary affection is crucial in the clinical management of these patients. In the current study, we aim to investigate the patterns of interstitial lung disease (ILD) associated with SSc patients (SSc- ILD) and their relation to serologic markers and clinical parameters. Methods: A cross-sectional study was undertaken on thirty-four adult SSc patients who met the 2013 ACR/EULAR criteria for SSc and Forty healthy controls of matched age and sex. The patients were subjected to history taking, clinical examination, skin assessment using the modified Rodnan Skin Score (mRSS), chest x-ray (CXR), pulmonary function test (PFTs), and high resolution computed tomography of the chest (HRCT). Routine laboratory tests were conducted in addition to immunologic tests and an enzyme-linked immunosorbent assay (ELISA) to determine the IL-33 level. Results: ILD was found in 23 SSc patients (67.6%); 20 patients had diffuse type while 3 patients had limited type. Non-specific interstitial pneumonia (NSIP) was found in 56.5%, usual interstitial pneumonia (UIP) was found in 21.7%, pleuroparenchymal fibroelastosis (PPFE) was found in 8.7%, and organizing pneumonia (OP) with the mixed pattern was found in 13% of SSc patients. Additionally, the mean IL-33 level in SSc patients was 98±12.7 compared to 66.2±10.6 in the control group (p < 0.001), with ILD patients having a significantly higher level (101.7±13.4) than those without (90.4±6.2), and a strong positive correlation with mRSS. Conclusion: Even in asymptomatic patients with SSc, ILD is prevalent, with NSIP being the most common pattern. IL-33 could be considered a potential biomarker for predicting the presence of ILD in SSc patients.