What is purpura?

• The term purpura is used to describe red-purple lesions that result from the extravasation of blood into the skin or mucous membranes – Purpura may be palpable or non-palpable (flat/macular) – Macular purpura is divided into two morphologies based on size: Petechiae: small lesions (< 3 mm). Ecchymoses: larger lesions(>5mm) • The type of lesion present is usually indicative of the underlying pathogenesis: i) Macular purpura is typically non-inflammatory ii)Palpable purpura is a sign of vascular inflammation (vasculitis) • All forms do not blanch when pressed. Diascopy refers to the use of a glass slide to apply pressure to the lesion in order to distinguish erythema secondary to vasodilation (blanchable with pressure), from erythrocyte extravasation (retains its red color) • Purpura may result from hyper- and hypo-coagulable states, vascular dysfunction and extravascular causes