Mongolian spots

Noun

Mongolian spot (plural Mongolian spots)

1. A benign, flat, congenital, usually blue to blue-black birthmark on the lower back with wavy borders and irregular shape, prevalent among East Asians, South-East Asians, Central Asians, Siberians, Polynesians, Native Americans and East Africans. It normally disappears three to five years after birth and almost always by puberty.
   • Mongolian spots are produced by melanocyte leftovers that do not migrate into the epidermis; they remain deeper than usual in the lumbar-sacral region, resulting in blue coloration of the skin. Mongolian spots occur mainly on the buttocks and lower back, and occasionally on the abdomen, thighs, and...1995, Theresa Overfield, Biological Variation in Health and Illness: Race, Age, and Sex Differences, page 13

   Synonyms:

   congenital dermal melanocytosis, dermal melanocytosis, Mongoloid spot