Mongolian spot is an area of gray—blue pigmentation of the skin present from birth, having a rounded or irregular shape. Most often, pigmentation is located in the lumbosacral region. This formation is one of the forms of congenital pigmented nevi. In the diagnosis of the Mongolian spot, its differentiation with melanoma-threatening neoplasms is important. As a rule, pigmentation gradually disappears during the first 4-5 years of life. No treatment is required.
The Mongolian spot got its name due to the fact that 90% of children belonging to the Mongoloid race are born with it: Chinese, Koreans, Vietnamese, Japanese, as well as Indonesians, Indians, Eskimos and Ainu. The Mongolian spot is often found in newborns of the Negroid race and only in 1% of Caucasians. Due to its localization in the sacrum area, the spot is also called a “sacral spot”.
As you know, the skin consists of 2 layers: the superficial — the epidermis and the deeper — the dermis. The cells that produce the pigment melanin, which causes skin color, are located in the epidermis and are called melanocytes. In persons of the Caucasian race, the formation of melanin occurs mainly under the influence of ultraviolet rays, resulting in a tan. In people of other races, melanin production occurs constantly, giving the skin a certain color. Moreover, the color of the skin depends not on the number of melanocytes, but on their functional activity.
In the process of embryonic development, melanocytes migrate from the ectoderm to the epidermis. Modern dermatology believes that the formation of the Mongolian spot is associated with the incomplete completion of this process, when part of the melanocytes remains in a deeper layer of the skin — the dermis. The melanin produced by them is the cause of gray-cyanotic skin staining.
The Mongolian spot is a congenital nevus. Its color can be gray-blue, bluish, less often bluish-brown. The uniformity of staining over the entire surface of the stain is characteristic. Pigmentation can have an oval or rounded shape, but irregular spots are more common. The size of the spot is also variable, as is its shape. It can be the size of a small coin and reach more than 10 cm in diameter, while covering an entire part of the newborn’s body (lower back, buttock or back).
As a rule, the spot is located in the lower back and sacrum, but it can be localized on the skin of the back, the back surface of the lower leg, buttocks and other parts of the body. In some cases, there is a migration of the spot, i.e. its displacement from the original position (for example, from the sacrum to the buttock). A single Mongolian spot is typical, but there are also multiple spots of different localization.
For the first time after the birth of a child, the color of the Mongolian spot may become more saturated, but then it decreases in size and fades. Usually pigmentation disappears completely by 4-5 years of a child’s life, less often — by 7-13 years. In some cases, it persists in adults. This is more often the case in the case of multiple spots that do not have a characteristic localization.
In dermatology, there has not been a single case of transformation of the Mongolian spot into melanoma. Therefore, along with papillomatous and verrucous nevus, intradermal pigment nevus and Setton nevus, the Mongolian spot belongs to melanomone-dangerous nevi.
If a pigmented nevus is found in a child, a consultation with a dermatologist is desirable. A doctor’s examination will allow you to accurately diagnose and differentiate the Mongolian spot from other congenital nevi. It is especially important to exclude the presence of melanoma-threatening formations (blue nevus, giant pigment nevus, Ota nevus, borderline pigment nevus) that require observation and treatment.
To differentiate the Mongolian spot with other nevi, dermatoscopy, syascopy and skin biopsy in the area of pigmentation can be performed. Histological examination of the spot reveals dendric cells containing melanin located in the lower layers of the dermis between unchanged elastic and collagen fibers (normally they are absent there).
When establishing an accurate diagnosis of the Mongolian spot, treatment is not required.