a brown to blue-black spot on the lower back and buttocks at birth, caused by a concentration of pigment-producing cells; usually disappears by the age of 3 or 4 years

A large birth mark which looks light blue, usually on the lower body. It disappears or becomes less noticeable as the baby grows. They are more common in Asian and dark-skinned babies.

A large birth mark that looks light blue, usually on the lower body. Disappears or becomes less noticeable as baby grows. More common in Asian and African American babies.

Large bluish birthmarks, usually on the lower back or buttocks, more common in darker skinned babies. Usually fade or disappear as a baby grows.

The term Mongolian Spot(s) or Mongolian Blue Spot refers to the smooth blue-gray or slighty brown patches which can be found on the lower back and buttocks area of some East Asian and Native American Infants and babies. It may look somewhat like a bruise or rash. It normally vanishes three to five years after birth and almost always by puberty.