Purpura is the name given to the discolouration of the skin or mucous membranes due to haemorrhage from small blood vessels.
Petechiae are small, purpuriclesions up to 2mm across
Ecchymoses or bruises are larger extravasations of blood.
Palpable purpura is purpura than can be felt, due to inflammation of the blood vessels (vasculitis)
Pigmented purpura is a sign of petechial haemorrhages associated with capillaritis
Extravasated blood usually breaks down and changes colour over a few weeks from purple, orange, brown and even blue and green.
Classification of purpura
There are many different types of purpura. Their classification depends on the appearance or cause of the condition.
Platelet disorders
Thrombocytopaenic purpura—due to destruction of platelets
Primary (idiopathic) thrombocytopaenic purpura due to autoimmune or unknown reasons
Secondary thrombocytopaenic purpura due to external or internal factors such as drugs, infections, systemic diseases
Other coagulation disorders
Disseminatedintravascular coagulation – clinical picture varies from a severe and rapidly fatal disorder (purpura fulminans) to a relatively minor disorder
Heparin induced thrombocytopenia – purpura and necrosis due to anti-platelet antibodies inducing platelet plugs that block blood vessels
Warfarin-induced necrosis – purpura and necrosis due to blood clots related to relative protein C deficiency early in treatment
Vascular disorders
Non-thrombocytopaenic purpura—leakage of blood through the vessel wall
Damage to small blood vessels
Increase in intraluminar pressure
Deficient vascular support, as in aged or sun damaged skin (senile purpura)
What are the signs and symptoms of purpura?
The signs and symptoms of purpura vary according to the type of purpura. The following broad generalisations may be made.
Petechiae are usually present in thrombocytopaenic purpura. There may be some external bleeding and bruising.
Coagulation defects usually present as large ecchymoses and external bleeding. Petechiae do not feature.
Inflamed blood vessels (vasculitis) cause persistent and localised purpura with an erythematousinflammatory component. This may be palpable. Ecchymoses and external bleeding are uncommon.
Suction bruise
Injury
Venousstasis
Vasculitis
Steroid purpura
Disseminated intravascular coagulation
What is the treatment for purpura?
The underlying cause of purpura should be identified and treated accordingly.
References
Book: Textbook of Dermatology. Ed Rook A, Wilkinson DS, Ebling FJB, Champion RH, Burton JL. Fourth edition. Blackwell Scientific Publications.
