Pulmonary capillaritis in diffuse alveolar hemorrhage

Light micrograph in pulmonary capillaritis showing marked broadening of the alveolar septa caused by edema and necrosis. There is a striking infiltration of neutrophils in the alveolar septa (arrows), with many of those cells undergoing fragmentation and appearing pyknotic. The alveolar spaces are packed with red blood cells (diffuse alveolar hemorrhage) as well as some neutrophils.