A comparative study of different types of connective tissue-associated interstitial lung disease.

Introduction: Interstitial lung disease (ILD) is an important pulmonary complication of connective tissue disease (CTD). This study aimed to analyze high-resolution computed tomography (HRCT) manifestations of different connective tissue-associated interstitial lung diseases (CTD-ILDs) to improve diagnostic accuracy.

Method: This study retrospectively included 99 patients diagnosed with CTD-ILD between September 2017 and July 2024. Visual assessment and quantitative CT analysis were used to evaluate HRCT manifestations.

Results: The age of the rheumatoid arthritis (RA) group was significantly greater than that of the polymyositis/dermatomyositis (PM/DM) and systemic sclerosis (SSc) groups (p = 0.025 and p = 0.02), with a mean age of 64.4 ± 10 years. The most common HRCT pattern of CTD-ILD was nonspecific interstitial pneumonia (NSIP) (p = 0.008); the adjusted residual > 1.96, usual interstitial pneumonia (UIP) was most frequently observed in the RA group, organizing pneumonia (OP) was most commonly observed in the PM/DM group, and lymphocytic interstitial pneumonia (LIP) was observed only in the primary Sjögren's syndrome (pSjS) group. The CTD-ILD groups exhibited significant differences in bronchiectasis (χ2 = 11.256, p = 0.0022), esophageal dilatation (χ2 = 33.923, p < 0.001), mediastinal lymph node enlargement (χ2 = 10.103, p = 0.041), and thin-walled cysts (χ2 = 14.081, p = 0.006). Adjusted residual > 1.96, esophageal dilatation was commonly observed in the SSc group; bronchiectasis was more common in the RA group; mediastinal lymph node was more common in the pSjS group. Statistically significant differences in the predominance of different CTD-ILDs (χ2 = 20.814, p = 0.0046). The PM/DM group exhibited significant consolidation and reticulation. The extensive honeycombing was present in the RA-ILD group (p = 0.044). Based on logistic binary regression analysis, bronchial dilatation (odds ratio: 4.506, p = 0.005) and extensive honeycombing (odds ratio: 1.282, p = 0.021) were significant predictors of RA-ILD, while lymph node enlargement (odds ratio: 3.314, p = 0.039) and thin-walled cysts (odds ratio: 6.278, p = 0.001) were predictors of pSjS-ILD.

Conclusion: Different types of CTD-ILD have characteristic HRCT manifestations.

Clinical trial number: As this study involved standard clinical procedures and assessments without an experimental treatment protocol, it did not require registration with a public clinical trials registry.