Mongolian spot

Mongolian spot
Classification and external resources
Mongolian spot visible on six-month-old Taiwanese baby girl
ICD-10	D22.5 (ILDS D22.505)
ICD-9	757.33
DiseasesDB	8342
eMedicine	derm/271
MeSH	D049328

A Mongolian spot (also known as "Congenital dermal melanocytosis,"^[1] and "Dermal melanocytosis"^[1]) is a benign flat congenital birthmark with wavy borders and irregular shape, most common among East Asians and named after Mongolians by Erwin Bälz.^[2][3]It is also extremely prevalent among East Africans, Polynesians, and Native Americans.^[4][5] It normally disappears three to five years after birth and almost always by puberty.^[6] The most common color is blue, although they can be blue-gray, blue-black or even deep brown.

Origin

The Mongolian spot is a congenital developmental condition exclusively involving the skin. The blue colour is caused by melanocytes, melanin-containing cells, that are deep under the skin. ^[5] Usually, as multiple spots or one large patch, it covers one or more of the lumbosacral area (lower back), the buttocks, flanks, and shoulders.^[5] It results from the entrapment of melanocytes in the dermis during their migration from the neural crest to the epidermis during embryonic development.^[5]

The condition is unrelated to gender; male and female infants are equally predisposed to Mongolian spot. The spots are harmless.^[5] However, recent research has shown that Mongolian spots may occur more commonly in children with certain rare metabolic conditions, such as mucopolysaccharidosis, Niemann-Pick syndrome and GM1 gangliosidosis. ^[7]

Among those who are not aware of the background of the Mongolian spots, it may sometimes be mistaken for a bruise. ^[8]

Prevalence

Mongolian spots are most prevalent among Mongols, and other Asian groups, such as the Chinese, Japanese, and Koreans. Nearly all East Asian infants are born with one or more Mongolian spots. It is also common if only one of the parents is East Asian. They also occur in 90-95% and 85-90% of East African and Native American infants, respectively.^[4] Approximately 90% of Polynesians and Micronesians are born with Mongolian spots as are 46% of Hispanic children.^[9]

The incidence among Caucasians from Europe is between 1-10%.^[4] It has been found to be more prominent among Europeans that have had extensive historical interaction with Asian invading cultures, such as the Hun, or among those who are originally of a central Asian origin, most notably among the Hungarians who have a 22.6% occurrence rate among their population.^{[citation needed]}

There is an incidence of 50-70% among the countries of the Americas,^[4] as a result of the Native American admixture found in mestizos (people of mixed European and Native American ancestry) that is an important racial group among some countries.

See also

• List of cutaneous conditions

References