Nonspecific interstitial pneumonia pattern as pulmonary involvement of rheumatoid arthritis.

The pathologic patterns of lung involvement were evaluated in 16 patients with rheumatoid arthritis (RA). They consisted of six females and ten males, with a median age of 67.5 years and diagnosed according to the American Rheumatism Association revised criteria. High-resolution computed tomography (HRCT) of the lungs was performed in all patients, and honeycomb formation was apparent in seven. Histopathologically, seven patients were diagnosed with usual interstitial pneumonia (UIP) pattern, seven with nonspecific interstitial pneumonia/fibrosis (NSIP) pattern, and two with UIP/NSIP hybrid pattern. There were no apparent honeycomb formations on HRCT in patients diagnosed with NSIP pattern. In conclusion, the present study demonstrates that NSIP pattern is also a significant histologic classification of interstitial pneumonia associated with RA.