Histopathologic subsets of fibrosing alveolitis in patients with systemic sclerosis and their relationship to outcome

Fibrosing alveolitis associated with systemic sclerosis (FASSc) has a better prognosis than idiopathic pulmonary fibrosis. In view of recent reports that idiopathic nonspecific interstitial pneumonia (NSIP) has a better prognosis than idiopathic usual interstitial pneumonia (UIP), we classified histologic appearances of surgical lung biopsies performed in 80 patients with FASSc. NSIP (n = 62, 77.5%), subcategorized as cellular NSIP (n = 15) and fibrotic NSIP (n = 47) was much more prevalent than UIP (n = 6), end-stage lung disease (ESL, n = 6), or other patterns (n = 6). There were 25 deaths (NSIP 16/62, 26%; UIP/ESL 6/12, 50%). Five-year survival differed little between NSIP (91%) and UIP/IESL (82%); mortality was associated with lower initial carbon monoxide diffusing capacity (DLCO) and FVC levels (p = 0.004 and p = 0.007, respectively). Survival and serial FVC and DLCO trends did not differ between cellular and fibrotic NSIP. Increased mortality in NSIP was associated with lower initial DLCO levels (p = 0.04), higher BAL eosinophil levels (p = 0.03), and deterioration in DLCO levels during the next 3 years (p < 0.005). We conclude that NSIP is the histopathologic pattern in most patients with FASSc. However, outcome is linked more strongly to disease severity at presentation and serial DLCO trends than to histopathologic findings.