|Birthmarks are simply clumps of blood vessels close together.|
The term "birthmark" can refer to all sorts of spots. One common type is the "hemangioma," which results from the clumping of several blood vessels in one spot.
"Port-wine stains" are one instance of these harmless blotches. Others are bright red bumps (the "strawberry hemangioma"), and most disappear before adulthood.
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