Mongolian Spot, Birthmark, Causes, Treatment, Pictures

Mongolian Spots
Mongolian Spots

A Mongolian spot is a type of birthmark that is present at birth. It usually disappears within the first years of life. Mongolian spots are usually seen on the lower back, buttocks, and legs and rarely on the face and hands. They are more prevalent in children of color. Here, find out more about the causes, variations, diagnosis, and treatment for these very common birthmarks.

What are Mongolian Spots?

Mongolian Spots are also known as Mongolian Birthmarks or Congenital Dermal Melanocytosis. They are flat grey, bluish, green or brown areas of skin. They are simply areas of skin where pigment cells known as melanocytes have been trapped under the dermis.

Mongolian Spots on Buttocks, Back and Hands
Mongolian Spots on Buttocks, Back and Hands Courtesy of the Indian Journal of Dermatology, Venereology and Leprology. 

How do they Form?

Melanocytes are cells located on the stratum germinativum which is the lowest layer of the epidermis.They are responsible for the production of melanin which gives the skin its pigment. It transports this color to the skin cells through melanosome which is cellular vesicles.

The epidermis and dermis are loosely connected through the papillary layer which has a loose connective tissue that contains nerve fibers, capillaries, and collagen and elastin fibers.

The quantity of production and amount transported to the skin cells is what determines the skin color or pigment. This means that in dark skinned persons there is a higher number of active melanocytes and subsequent melanin.

During melanin production, some of the melanocytes may slip through the loose connective papillary layer and get trapped in the reticular layer of the dermis. This alters their DNA and causes pigment related birthmarks referred to as Mongolian spots.

Also referred to as congenital dermal melanocytosis they occur within the mother’s womb. The spots are formed in the fetus and can be spotted immediately at birth or after a few weeks.

Causes of Mongolian spot on Baby

Trapped melanocytes

The sperm and egg are covered by melanin.As the zygote develops the neural tube that contains neural crest cells supplies the melanocytes in the form of melanoblasts to the embryo.

In an embryo, the melanoblasts are first deposited in the dermis at twelve weeks before they are transported to the epidermis and hair follicle. This helps to give infants their color.

However, if a majority of the melanoblasts are still trapped in the dermis after the fourteenth week, they clump up. They eventually mature to melanocytes and start producing their own melanin in large quantities. Though there is a need for smaller quantities melanin in the dermis, this high melanin isn’t transported to the skin cells and surface through the dermo-epidermal junction.

The entrapment blocks the production of melanosomes which are important for melanin transportation to the surface. They remain entrenched causing the spots.

Mongolian Birthmark
Mongolian Birthmark

Race and genetics

In darker pigmented persons especially the Asians, Africans and East Indians there is high melanin production. In a non-mixed conception, the egg and sperm both will contain very active melanoblasts which are passed on to the embryo. Due to their activeness, some melanocytes are likely to be trapped in the dermis causing the spots.  These particular melanocytes produce Eumelanin known for its black or deep brown hue (Tarrytown, 2008).

Receptor blockage

The movement of melanoblasts through the dermis to the epidermis is facilitated by receptors such as tyrosine kinase and extracellular vesicles. The presence of metabolites and histamines in the dermis cells that contain sulfate may attach to the receptors causing a blockage and shifting the migration process.

Inborn errors

Metabolism problems which are gene related also cause an effect. Trapped and clumped melanocytes create a negative chemotaxis where they produce enzymes. This interferes with the enzymes specific function of breaking down carbohydrates, fats, and proteins.

This creates cell disconnection between the neural crest cells and the keratinocytes (skin cells) thus creating the Mongolian spot. Gangliosidosis in infants is one of the causes due to the production excess mucopolysaccharides which block cell connection.  The mucopolysaccharides are associated with Hurlers disease and Hunters’ syndrome (Tay, 2015)

This is because they attach to the tyrosine kinase receptor affecting the nerve growth.

Neurocristopathies is an infant disorder which interferes with melanoblasts’ migration through the neural crest.  The disorder creates a connectivity issue between the skin cells and the melanocytes. In the process, the keratinocytes release elements through positive chemotaxis. This substance may further block the release of melanocytes from the dermis area. (Gupta, Thappa 2013)

Mongolian Spot on White Baby

Mongolian spots are rare in white children. According to, they appear on about 10% of white children compared to 90% in children with pigmented skin.

On the other hand, more than three-quarters of children born of African, Asian or Mediterranean descent have Mongolian spot.

Characteristics of Mongolian spot

They are deeply pigmented in the dermis and not very exposed to light

When they appear on the surface they have a lighter hue making them appear brown. When deeper in the skin they appear bluish gray.

Appear flat, oval shaped with wavy borders

Since they are benign in nature they are non-inflamed in nature thus don’t extend beyond the skin. More so they are formed in the deepest skin layers hence are unable to penetrate the upper skin level (Baren, 2008)

Mongolian spot on leg and arm in babies
Mongolian spot on leg and arm in babies

Can measure between 2- 20 cm

The large size occurs when a large number of melanocytes sip through the papillae into the reticular layer. This layer is denser and more defined and it is linked to the fibroblasts, sebaceous glands, and hair follicles. This means that any melanin production at this layer will have a larger effect and appearance.

If it slips into the papillae it may have a smaller size such as 2cm

One or many spots

Each spot or area contains a number of melanocytes and if they are clumped together they form one big spot. However, the spots have a very normal skin texture without any lesions or bruises.

Appear on a specific area

The melanocytes migration occurs through the neural crest which connects the brain to the sacro-gluteal and lumbar which are lower areas of the spine. This is why the Mongolian spot often affects the buttock and lower back area. But they can also appear on shoulders and legs in extreme cases.

Intense but fades with time

The dermis contains strong connective tissues which cover all the available cells. These melanocytes are covered in strong fibers and granules that give them an extracellular sheath. As the baby begins to grow the surrounding fibers weaken thus fading away from the spots.

Also once the baby is born its exposure to sunlight triggers the formation of collagen. More collagen means extended fibers which constrain the existing dermal melanocytes.

Variants of the Mongolian spot

Based on the characteristics there can be variations in the appearance of the spots if the DNA is altered. They include:

Abnormal Mongolian birthmark which appears on the face. The entrapment of the melanocytes in the reticular layer squeezes them against the hair follicles and sebum tissues present. This may make them appear hairy.

Deep blue Mongolian spot which is entrenched in the deepest skin layers. They have well-defined borders and have a deeper color that appears black. They take a longer time to fade from the skin usually up to puberty.

Persistent Mongolian spots. They appear very large and have very sharp borderlines. They spread to adulthood since they attach themselves to the blood vessels making it difficult to fade.

Do Mongolian Spots go away?

Mongolian spots usually disappear before the child’s sixth birthday. If they are present in their teens, they are likely to be permanent markings.

Mongolian Spot in Adults

A very small percentage of these advance to adulthood. It is not clearly understood why some of these birthmarks persist to adulthood in some people. It is important to note that bluish markings that appear in adulthood are not Mongolian Birthmark spots.

Mongolian Spot Treatment

Mongolian spots are benign in nature and may only require treatment when they are spotted in adulthood. Most of them disappear on their own by the time the child is five years old.

Laser treatment can be used if it extends to puberty and adulthood. Though not highly recommended the use of light converts to heat energy which hits the dermis melanocytes inhibiting melanin production. The heat also destroys the extracellular sheath thus fading away from the spots.

Cosmetic camouflage which makes use of topical creams to cover the marks. Highly rich in lanolin and wax oil compounds once applied it can be removed after four days. Loose powder is both before and after application to help hold the cream.

How to Differentiate Mongolian Spots from Bruises

Mongolian spots have been often been mistaken for bruises. These may trigger an accusation of child abuse especially with parents who do not have any experience with them.

In this light, it is recommended that the pediatrician or case workers in cases of adoption should acknowledge them. Ensure that they put the presence of Mongolian spots into their records.

The major difference between this birthmark and bruises is that bruises change in shape and size over time. Mongolian spots, on the other hand, take time to fade. Bruises may be painful to touch while Mongolian spots do not.

Mongolian Spots Pictures

Mongolian Spots
Mongolian Spots



Gupta, D, Thappa DM. Mongolian spots. Indian J Dermatol Venereol Leprol (online) 2013 Cited 2017 June 26. Available from:

Silverberg, N. B., In Durán-McKinster, C., & In Tay, Y.-K. (2015). Pediatric skin of color.

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