In hyaline membrane disease, the pathology in the lung consists of -

Morphological changes in ARDS Diffuse alveolar damage is the characteristic histological manifestation of ARDS. In the acute stage, the lungs are heavy, firm, red and boggy with congestion, interstitial and intra-alveolar edema. The alveolar walls become lined with a waxy haline membrane. The hyaline membrane consists of fibrin-rich edema fluid mixed with the cytoplasmic and lipid remnants of necrotic epithelial cells. Resolution is unusual, more commonly, there is an organization of the fibrin exudate, with resultant intra-alveolar fibrosis.