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/ESL (82%); mortality was associated with lower initial carbon monoxide diffusing capacity (DL(CO)) and FVC levels (p = 0.004 and p = 0.007, respectively). Survival and serial FVC and DL(CO) trends did not differ between cellular and fibrotic NSIP. Increased mortality in NSIP was associated with lower initial DL(CO) levels (p = 0.04), higher BAL eosinophil levels (p = 0.03), and deterioration in DL(CO) 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 DL(CO) trends than to histopathologic findings.

These data suggest that sarcoidosis and idiopathic pulmonary fibrosis are the most frequent ILDs in our population. In comparison with the few previous reports, interesting dissimilarities have been observed.

The term "acute interstitial pneumonia" (AIP) describes an idiopathic clinicopathological condition, characterized clinically by an interstitial lung disease causing rapid onset of respiratory failure, which is distinguishable from the other more chronic forms of interstitial pneumonia. It is synonymous with Hamman-Rich syndrome, occurring in patients without pre-existing lung disease. The histopathological findings are those of diffuse alveolar damage. AIP radiologically and physiologically resembles acute respiratory distress syndrome (ARDS) and is considered to represent the small subset of patients with idiopathic ARDS. It is frequently confused with other clinical entities characterized by rapidly progressive interstitial pneumonia, especially secondary acute interstitial pneumonia, acute exacerbations and accelerated forms of cryptogenic fibrosing alveolitis . Furthermore, many authors use the above terms, both erroneously and interchangeably. It has a grave prognosis with >70% mortality in 3 months, despite mechanical ventilation. This review aims to clarify the relative clinical and pathological issues and terminology.