I had to look it up in the dictionary ...
In Medicine ... "Purpura is a disease marked by livid spots on the skin or mucous membranes caused by extravasated blood" ...
Meaning, a disease, caused, when blood is forced out of its normal channels, into the surrounding tissue, causing light swellings and/or the spotted discolration of Skin.
THE TWO PRONGED TREATMENT.
Under normal Circumstances, it is due the "seepage" of Blood from its normal channel, into the surrounding Tissue ...
This seepage, in all probability, is caused by the "Constriction" of "Veins" ... causing the veins to burst and spill blood, into the surrounding tissue ... this spill appears as spots.
Therefore ... The Loss of the Natural "Flexibility" of Veins, is the main Issue.
This can be Tackled, by
[i] Improving the blood's flow, in Veins; by high intake, of Vitamin C
[ii] Once, further discoloration as spots, has stopped, gently massage the effected area, with Olive oil, till, the normal coloration of Skin has been restored.
But do consult a Dermatologist ... Skin Doctor ... who can determine, the "exact" cause of the spots ... for skin spots can also appear, due infection caused by other than the Purpura condition.