CT features of interstitial lung disease in systemic lupus erythematosus and overlap lupus-other connective tissue disease.

Abstract

To describe initial and follow-up CT features of chronic interstitial lung disease (cILD) associated with systemic lupus erythematosus (SLE), focusing on variant signs of lung fibrosis. This multicentric retrospective study included 76 patients (72 females, 95%, median age: 46 years) with both cILD and SLE, including 46 patients having another connective tissue disease (CTD) associated with lupus. Two radiologists independently reviewed chest CTs for ILD pattern and variant fibrosis signs. Radiologic progression of ILD was analyzed in 52 patients. Pulmonary function tests were collected at baseline and follow-up if available. Data were analyzed using Fisher's exact and Wilcoxon's rank sum tests. Inter-reader agreement was assessed using Cohen's Kappa coefficients. The most frequent ILD patterns were non-specific interstitial pneumonia (NSIP) in 31/76 (41%) patients, among which 5 showed overlap organizing pneumonia features, indeterminate in 18/76 (24%) patients, and usual interstitial pneumonia in 10/76 (13%) patients. The overall inter-reader agreement for the CT pattern was moderate (κ = 0.52). Any variant sign of fibrosis, including anterior-upper-lobe sign, exuberant-honeycombing, island-like fibrosis, and straight-edge sign, was observed in 14/76 (18%) patients, with an overall inter-reader agreement of 0.62, highly variable according to the sign considered. After 100 months of median follow-up, CT showed signs of progressive ILD in 36/52 (69%) patients, with poor correlation between functional and radiological progression. SLE-associated cILD most often showed an NSIP or indeterminate pattern, commonly associated with variant signs of lung fibrosis. After a median follow-up of 100 months, 69% of patients showed CT signs of progression. Question Radiologic presentation and progression of cILD in SLE remain poorly defined, limiting the ability to guide long-term clinical management. Findings NSIP (more common in isolated lupus) and indeterminate patterns predominated, with variant fibrosis signs of variable reproducibility. Two-thirds of patients showed progressive ILD. Clinical relevance CT helps characterize and monitor lupus-associated interstitial lung disease, but limited pattern reproducibility and weak correlation with functional decline support the need for multidisciplinary evaluation and individualized follow-up strategies.