Architectural remodelling in acute and chronic interstitial lung disease: fibrosis or fibroelastosis?

Aims: Pulmonary fibrosis in acute and chronic lung disease has been much in vestigated, but little attention has been directed at the elastic tissue in these situations. Our aim was to verify whether elastic deposition accompa nies collagen deposition in the repairing process of acute and chronic lung injury. Methods and results: We measured, by image analysis, the content of fibres of the collagenous and elastic systems of the alveolar septum in histologic al slides sampled from autopsied lungs, using the picrosirius-polarization method and Weigert's resorcin-fuchsin stain, respectively Five groups were studied: I, 10 normal patients; II, 10 patients with cardiogenic pulmonary oedema; III, 23 adult respiratory distress syndrome (ARDS) patients in the early phase; IV, 14 ARDS patients in the late fibroproliferative phase; and V, 10 idiopathic pulmonary fibrosis patients. The first two groups were us ed as controls. The content of fibres of the collagenous and elastic system s was significantly increased in groups TV and V as compared to the other g roups. Conclusions: Our results indicate that deposition of elastic system fibres is present in the fibroproliferative phase of ARDS and in usual interstitia l pneumonia and suggest that this event may contribute to the alveolar mech anical dysfunction and remodelling that occur in acute and chronic intersti tial lung disease.