Rheumatoid arthritis-associated interstitial lung disease (RA-ILD) is a major extra-articular manifestation of rheumatoid arthritis and a key determinant of patient outcomes. Among its radiologic subtypes, the usual interstitial pneumonia (UIP) pattern is the most frequent and clinically important; however, the definition and conceptual use of “RA-UIP” differ among disciplines and across countries, reflecting variations in how radiologic and pathologic features are integrated into clinical practice. RA-UIP shares several features with idiopathic pulmonary fibrosis (IPF) but also differs in pathogenesis, imaging characteristics, and clinical behavior, resulting in more heterogeneous prognoses and therapeutic responses. Although a recent international update proposed a unified classification encompassing both idiopathic and secondary interstitial pneumonias, secondary UIPs such as RA-UIP often show overlapping or combined morphologies that remain challenging to categorize and manage. This review emphasizes the dynamic interplay between joint and lung disease activity in RA-ILD conceptualized as a “virtuous” or “vicious” cycle. Stable control of arthritis can promote pulmonary stability, whereas uncontrolled systemic inflammation and treatment limitations—often complicated by infection—can destabilize both. While antifibrotic therapy can slow fibrotic progression, sustained inflammatory control remains essential for maintaining a favorable cycle. Integrating these dual perspectives, we outline a conceptual clinical-radiologic framework for interpreting UIP-like patterns in RA-ILD in relation to the balance between inflammation and fibrosis. Rather than serving as an evidence-based treatment algorithm, this flexible, patient-centered framework is intended to organize radiologic heterogeneity, support multidisciplinary therapeutic discussion, and generate hypotheses for future validation across autoimmune and other fibrosing ILDs.
Yamakawa et al. (Fri,) studied this question.