The Mongolian or blue spots (congenital dermal melanocytosis) appear in some newborns at the time of birth or in the first weeks of life. It acquires the name of "Mongolian spot", since it appears frequently in the Asian, American Indian, African and Indonesian races. It is present in 90% of newborns of these races, in Caucasians it only appears in 1-5% of cases, being somewhat more infrequent.
The newborn's skin appears stained with a blue, blue-green or blue-gray tone, mainly in the area of ​​the back, buttocks, shoulders and more rarely on the thighs, arms or feet. Its shape and size is varied, presenting diffuse edges, these characteristics make them be confused with hematomas from childbirth (bruises).
Its origin is in a accumulation of melanocytes (cells responsible for the production of melanin and protection from the sun's rays in the skin). The effects of light on these melanocytes that are found in the depth of the dermis are what give it that bluish color, as a consequence of the Tyndall effect (at that depth of the skin the red and yellow colors are not reflected).
If our child has these spots, we must know that they are usually benign, They do not have any significance for the health of our baby and will disappear spontaneously in the first years of age. The usual thing is that it disappears around 2 years, despite the existence of cases that last up to 9 or 10 years. It is always appropriate to consult with the pediatrician, who will confirm the presence of this birthmark and reassure us about it.
Once the child health specialist has diagnosed the presence of these spots, no follow-up is necessary, since as we discussed, they will disappear by themselves as our child grows.