Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc
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Diffuse alveolar damage (DAD) and acute interstitial pneumonitis (AIP) often present clinically as the adult respiratory distress syndrome. To evaluate the usefulness of histochemical techniques and to better understand the histopathologic changes of these diffuse lung injuries, postmortem lung sections of 14 and 33 patients who had been diagnosed as having DAD in organizing stage and AIP, respectively, were studied with the use of lectins and monoclonal antibodies against surfactant apoprotein (PE-10) and collagen type IV. On hematoxylin-eosin stained sections, type II pneumocyte hyperplasia and hyaline membrane formation were the major histopathologic findings in both DAD and AIP. ⋯ Hyaline membrane coating alveolar septal surfaces and exudate in alveolar air spaces were also stainable with PE-10. Surfactant apoprotein remained demonstrable histochemically within type II pneumocytes and hyaline membrane despite severe inflammatory injuries of the lungs. The immunohistochemical stain using anti-collagen type IV antibody revealed discontinuous alveolar basement membrane in 50% of DAD patients with respirator use and 80% of AIP patients with steroid medication.