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Mongolian spot

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noun, plural: mongolian spots

A pigmented birthmark that is dark-bluish in color, flat, with wavy borders and irregular shape, occurring usually on the sacral region, posterior thigh, leg, back, or shoulder, and frequently seen in coloured children


Birthmarks are marks on the skin at birth or shortly afterwards. One of the two major types of birthmarks is the pigmented birthmark (the other, vascular birthmark). Pigmented birthmarks are those that are associated with a localized overgrowth of melanocytes. They include moles, café au lait spots, and mongolian spots.

Mongolian spots are birthmarks that are usually dark bluish in color. They may also be blue-gray or deep brown. They are flat, with wavy borders and irregular shape. They are present at birth and usually occur on the sacral region, posterior thigh, leg, back, or shoulder of certain newborns (frequently those with dark skin). This birthmark usually fades away with age (often by the age of 4). Nevertheless, it may persist in certain individuals. The birthmark is named after Mongolians by German anthropologist, Erwin Bälz, who was the first to describe it in 1883 in Japan.

Mongolian spots are caused by an accumulation of the melanin-producing cells (melanocytes) in the affected area when the melanocytes are trapped in the dermis during embryonic development, particularly during their migration from the neural crest to the epidermis.


  • (congenital) dermal melanocytosis
  • blue spot

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