Petechial hemorrhages. A review of pathogenesis.

Petechial hemorrhages are areas of pericapillary bleeding that occur in a wide spectrum of disorders, including some of particular forensic interest. Since their potential significance was first recognized by Tardieu in 1855, attention has largely focused on their diagnostic importance. There have been only a few studies of their mechanism of production. Although the pathogenesis of petechiae is often conjectural, it seems that, in spite of their stereotypical gross appearance, a variety of pathogenetic mechanisms may be involved. They range from mechanical disruption of the capillary wall to subtle cellular injury that permits the transit of red blood cells through the endothelial cytoplasm. I discuss several conditions that are commonly encountered in forensic practice, with emphasis on petechial hemorrhages and their pathogenesis.