Interstitial Lung Disease in Rheumatoid Arthritis: Clinical Diagnostic Challenges

Abstract

Interstitial lung disease (ILD) represents a major extra-articular manifestation of rheumatoid arthritis (RA) and is associated withsubstantial morbidity and mortality. Pulmonary involvement in RA is heterogeneous, affecting the lung parenchyma, airways, pleura,and pulmonary vasculature, with RA-associated ILD (RA-ILD) being the most clinically significant manifestation. RA-ILD maydevelop after the onset of joint disease or, in some cases, precede articular symptoms, posing diagnostic challenges for clinicians.Multiple factors contribute to RA-ILD development, including genetic susceptibility, environmental exposures, particularly cigarettesmoking, and immune-mediated mechanisms involving protein citrullination and autoantibody production. High-resolution computedtomography (HRCT) remains the cornerstone of diagnosis, allowing identification of characteristic interstitial pneumonia patternssuch as usual interstitial pneumonia (UIP) and nonspecific interstitial pneumonia (NSIP). However, many RA patients exhibitradiological abnormalities in the absence of respiratory symptoms, and not all detected abnormalities progress to clinically significantdisease. Pulmonary function tests, bronchoalveolar lavage, and histopathology provide supportive information but have limitationsin screening and diagnosis. A subset of patients develops progressive pulmonary fibrosis, which is associated with worseningrespiratory function and increased mortality. The absence of validated screening strategies and the overlap of RA-ILD with otherpulmonary conditions further complicate timely diagnosis. This review highlights current diagnostic approaches and emphasizesthe challenges in identifying RA-ILD and its progressive forms, underscoring the need for multidisciplinary evaluation and improvedrisk stratification.