Two experienced pathologists (M.O. and M.K.) reviewed the archived haematoxylin and eosin (HE)-stained slides to confirm the findings of DAD. One representative paraffin block containing the alveolar region, reflecting the acute phase of DAD (Fig. 1a) was selected for immunohistochemical analysis in each case. Most cases showed acute phase DAD lesions as well as organizing phase DAD lesions (Fig. 1b). In some cases, lesions only showing the acute phase of DAD changes were found, with no appreciable lesions showing the organizing phase of DAD changes. At the same time, areas that were thought to be more affected by smoking, such as emphysematous areas, were excluded. All the tissue samples were fixed in formalin and embedded in paraffin. Serial tissue Sects. (3 μm-thick) were prepared for HE staining and immunohistochemical analysis.

Histopathology of autopsy specimens of the acute phase (a) and the organizing phase (b) of diffuse alveolar damage (DAD). Haematoxylin and eosin staining. In the acute phase, oedema and hyaline membrane formation are observed (a). In the organizing phase, granulation tissue forms in the alveolar walls and spaces (b). Original magnification × 100