Purple colouration

The many disorders causing purple marks or discolouration in the skin are defined in this chapter with short summaries and clinical images for many. Differentiation is made between petechiae and purpura, and important causes are outlined. These include trauma (bruising); abnormalities of platelets and other clotting factors; vessel fragility and sepsis. Particular attention is given to meningococcal septicaemia and its diagnosis and management according to national guidelines. A short section on other infective causes is also included. There is a description of the investigation and management of cutaneous vasculitis that includes Henoch–Schönlein purpura. Special considerations for purpura in the neonate are given and the chapter ends with the diverse causes of purple patches other than purpura.