Purpura simplex is increased bruising that is due to fragile blood vessels.
Purpura simplex is extremely common. The cause is not known. Some doctors think it may be a feature of many disorders, but others think it is a normal variation.
The disorder usually affects women. Bruises develop on the thighs, buttocks, and upper arms in people without known injuries. People may have family members who also bruise easily. Although doctors often do blood tests, no abnormalities are found.
This condition is not serious, and no treatment is needed.
Last full review/revision January 2013 by David J. Kuter