Purpura and Ecchymosis are terms indicating spontaneous bleeding under the skin surface. They do not have a traumatic cause. Purpura is a smaller lesion as compared to Ecchymosis. Blood that leaks from broken microvasculature collects under the skin in patches of various sizes. Both these lesions are more visible in children and the elderly who have fragile microvasculature. Various conditions can cause bleeding in the skin leading to either purpura or ecchymosis. Let us understand what causes these skin lesions and how do they differ from one another.
Purpura
The word Purpura has originated from the Latin language meaning red or purple. So Purpura refers to small reddish purple discolorations on the skin that do not blanch when external pressure is applied over them. They occur due to vitamin C deficiency or may be secondary to inflammatory disease of the blood vessels (vasculitis).
The discolorations are usually small measuring anywhere between 3mm to 10 mm and have more distinct borders. Purpura can be due to a variety of causes. Platelet disorders, coagulation disorders, vascular disorders such as vasculitis, chronic hypertension, blood vessel damage due to old age; meningitis, radiation complication, cocaine abuse, scurvy (Vitamin C deficiency) or even after blood transfusion.
Ecchymosis
The word Ecchymosis has originated from the Greek language which means reddish or bluish discolouration of the skin due to extravasation of blood from ruptured blood vessels. These patches of blood are larger than purpura and do not blanch on applying external pressure over them. It can have traumatic as well as non-traumatic causes. Ecchymosis occurring after a trauma is generally referred to as a bruise. Ecchymosis lesions are larger than the purpura and are more than 1cm diameters with more diffuse borders as compared to purpura.
One major cause of ecchymosis is blood coagulation disorders like Haemophilia A in children. Leukaemia, Acute renal failure, multiple myeloma and liver cirrhosis are some other common causes of ecchymosis. These lesions may or may not be painful. The area surrounding the ecchymosis lesion may be inflamed and the lesion may spread to surrounding areas depending on the size of the ecchymosis.
To summarise Purpura and Ecchymosis are reddish purple or bluish discolorations within the skin that occur spontaneously. They are non-raised lesions that change colour from red to purple or blue to yellowish green and finally disappear by the end of two weeks. Ecchymosis lesions are slightly larger than purpura.