Pathologic approach to pulmonary hemorrhage

The pathologist's approach to pulmonary hemorrhage is outlined. Most cases fall into those examples of pulmonary hemorrhage caused by localized sites of bleeding, and those examples that fall within the spectrum of diffuse alveolar hemorrhage. The histologic evaluation of pulmonary hemorrhage is outlined including assessment of fresh hemorrhage in alveolar spaces (including exclusion of traumatic hemorrhage related to the procedure) and the presence of hemosiderin and it's various causes. The most common causes of diffuse alveolar hemorrhage and clues to their clinically pathologic diagnosis are discussed.