Unless it affects sense or function, they're usually left untreated and go away by themselves after a few years.
But some birthmarks only get worse. Congenital Melanocytic Nevus manifests itself in discolored moles that may be hairy or hard.
An Qi, an eight year old from China was born with the large birthmark, which covers the right side of his face. As he's grown, the mark has expanded and also grown thick black hair.
Didier Montalvo lives in rural Columbia, and the neighbors shun him.
His mother thought his affliction was her fault, for looking at a solar eclipse while pregnant. Villagers refuse to acknowledge that silly superstition, convinced that the boy is cursed by evil forces.
Didier was teased and bullied by other kids, and his melanocytic nevus earned him the name "Turtle Boy."
His family was unable to afford the surgery that could correct the problem, but he tried to have as normal a life as possible.
Didier's life was severely affected by the growth, which was painful and itchy.
When his story was featured in a local newspaper, he received a flood of donations, and a plastic surgeon from Great Ormond Street Hospital in London offered to fly to Colombia to work with the team there.
Surgeon Neil Bulstrode said, “Didier’s CMN was the worst case I had ever seen due to the size and bulk of the lesion. Effectively three quarters of the circumference of his body was affected. When I saw the pictures of Didier, one of my first feelings was that if we could remove it, we would significantly improve his quality of life.”
This group of teens overcame their affliction by forming a martial arts team and fighting crime.