The pathologic characteristics of interstitial pneumonia cystic fibrosis. A retrospective autopsy study

Interstitial pneumonia is a poorly understood variant of lung injury in patients with cystic fibrosis (CF). The authors identified prominent interstitial pneumonia (defined as an inflammatory reaction predominantly involving alveolar septa) in 9 of 43 autopsied patients with CF. Lungs from these nine were studied by light microscopy to determine the histopathologic features, clinicopathologic correlates, and potential causes of CF-associated interstitial pneumonia. Two histologic variants were identified, alveoloseptal (in which the inflammatory reaction was confined to the alveolar wall) and organizing (in which intraalveolar granulation tissue was present in addition to septal inflammation), which respectively affected four and five patients. Cholesterol deposits and capillary proliferation were prominent associated features in some patients. Interstitial pneumonia was not diagnosed antemortem and was identified on chest roentgenogram in only two patients. There were no distinctive clinical features associated with different histologic subtypes, nor did histologic or clinical data identify a specific cause(s) of interstitial pneumonia. The authors conclude that CF-associated interstitial pneumonia, although usually an incidental finding at autopsy, may potentially contribute to respiratory impairment and death. Although there are multiple possible causes of interstitial lung injury associated with CF, the authors were unable to identify, with certainty, the pathogenesis of interstitial pneumonia in any patient in this study.