Histopathologic pattern and clinical features of rheumatoid arthritis-associated interstitial lung disease.

STUDY OBJECTIVES To investigate the histopathologic pattern and clinical features of patients with rheumatoid arthritis (RA)-associated interstitial lung disease (ILD) according to the American Thoracic Society (ATS)/European Respiratory Society consensus classification of idiopathic interstitial pneumonia. DESIGN Retrospective review. SETTING Two thousand-bed, university-affiliated, tertiary referral center. PATIENTS Eighteen patients with RA who underwent surgical lung biopsy (SLBx) for suspected ILD. METHOD SLBx specimens were reviewed and reclassified by three lung pathologists according to the ATS/European Respiratory Society classification. Clinical features and follow-up courses for the usual interstitial pneumonia (UIP) pattern and the nonspecific interstitial pneumonia (NSIP) pattern were compared. RESULTS The histopathologic patterns were diverse: 10 patients with the UIP pattern, 6 patients with the NSIP pattern, and 2 patients with inflammatory airway disease with the organizing pneumonia pattern. RA preceded ILD in the majority of patients (n = 12). In three patients, ILD preceded RA; in three patients, both conditions were diagnosed simultaneously. The majority (n = 13) of patients had a restrictive defect with or without low diffusion capacity of the lung for carbon monoxide (D(LCO)) on pulmonary function testing; 2 patients had only low (D(LCO)). The UIP and NSIP groups were significantly different in their male/female ratios (8/2 vs 0/6, respectively; p = 0.007) and smoking history (current/former or nonsmokers, 8/2 vs 0/6; p = 0.007). Many of the patients with the UIP pattern had typical high-resolution CT features of UIP. Five patients with the UIP pattern died, whereas no deaths occurred among patients with the NSIP pattern during median follow-up durations of 4.2 years and 3.7 years, respectively. CONCLUSIONS The histopathologic type of RA-ILD was diverse; in our study population, the UIP pattern seemed to be more prevalent than the NSIP pattern.