Petechiaeandpurpuraare two related symptoms that occur when tiny blood vessels calledcapillariesburst and leak under the skin.
Petechiae is essentially a smaller version of purpura.
Both can be sparked by the same conditions and treated in the same way.
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This article describes the symptoms and causes of petechiae and purpura, including how they are diagnosed and treated.
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Reproduced with permission from DermNet New Zealand and Raimo Suhonenwww.dermnetnz.org2023.
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They both cause skin discoloration and are non-blanching (meaning they don’t lighten when pressed).
Where they differ is in their size, shape, texture, and color.
By definition:
Areas that are larger than 10 mm are referred to asecchymosis, also known as bruising.
Petechiae usually appear as a cluster of tiny “bloodspots” that sit flat against the skin.
With purpura, one or many areas of discoloration may be irregular in shape and often raised.
The color of petechiae and purpura can also vary.
Because petechiae are smaller, they tend to be seen as bright red spots that vanish relatively quickly.
How Long Does Petechia and Purpura Last?
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The clot they form can help stop bleeding.
One way to help confirm the diagnosis is to press a water glass against the lesions.
If they do not blanch (turn white), it is a positive sign of petechiae or purpura.
Both also tend to develop suddenly rather than gradually.
With petechiae, there will typically be multiple spots rather than a single one.
In other cases, petechiae and purpura are treated by resolving the underlying condition.
If petechiae and purpura are due to severely low platelet counts, a blood transfusion may be needed.
Autoimmune causes may require treatment withimmunosuppressantsthat temper the overactive immune response.
This includes:
Summary
Petechiae and purpura are two related conditions resulting from the leaking capillaries.
Petechiae is characterized by blood spots under 4 millimeters that are typically red and flat.
Purpura is characterized by areas of discoloration between 4 and 10 millimeters that tend to purplish and slightly raised.
The diagnosis involves a physical exam and a review of your medical history.
A positive sign for purpura and petechiae is a non-blanching lesion.
Royal Children’s Hospital Melbourne.Clinical practice guidelines - petechiae and purpura.
Reyes MA, Eichenfield LF.Petechiae and macular purpura.
National Heart, Lung, and Blood Institute.Thrombocytopenia.
MedlinePlus.Bleeding into the skin.
