Mongolian Spot, also known as Congenital Dermal Melanocytosis or Dermal Melanocytosis is a flat blue gray like skin pigmentation occurring more frequently in darker skinned persons such as Native American and Asians healthy infants. They are harmless, not associated with any disease and no treatment is required. They usually fade away after 5 years of life or so.
Mongolian spot is usually present at birth but it can also occur within few days to weeks of birth. These spot are thought to occur due to entrapment of melanocytes (the pigment cells) in the dermis that have failed to reach the epidermis from neural crest during embryo development. The blue discoloration is due to the collection of pigment cells in deeper layer of dermis which gives bluish tone to the skin.
Mongolian spot usually are seen on lumbo-sacral area of a healthy infant but buttocks, flanks and shoulder may also be affected. In some cases it may also involve anterior or posterior trunk and extremities. Such cases are usually mistaken for bruises of child abuse. So, careful observation by a dermatologist is required. These lesions occurring on head, face, palm and soles have not been reported.
As these spots are harmless and not associated with any disease, no treatment is required or recommended. They fade away with in few year of life, usually within 3 to 15 years of life. But if they still persist after 15 years life they are more likely to remain permanent. In some few cases who has more widespread spots or unusual spots it may take longer to completely fade.
Related: Mongolian blue spot, child fleck, sacral fleck, newborn blue fleck, newborn sacral blue fleck, Semitic mark, Semitic stain, congenital dermal melanocytosis, dermal melanocytosis