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Congenital dermal melanocytosis (formerly called Mongolian blue spots) are a type of birthmark. The
term congenital dermal melanocytosis refers to one or more birthmarks.They are flat blue or blue/grey spots with an irregular shape that commonly appear at birth or soon after.
Although they may look like bruises, it is important to recognise that congenital dermal
melanocytosis are birthmarks, not bruises
Congenital dermal melanocytosis are most common at the base of the spine, on the buttocks, back and shoulders. They are extremely common among Asian children, as well as children with dark skin, including people of Polynesian, Indian and African descent.
If your child has congenital dermal
melanocytosis, they are otherwise healthy. The birthmarks are not associated with any other medical symptoms or illnesses, and do not cause any pain.
No treatment is needed or recommended. The spots do not cause any medical complications. The discolouration often fades within the first years of
life, and the birthmarks have usually gone once the child reaches adolescence. Less than 3 per cent of cases will continue into adulthood, and these are
usually the ones present in body sites
other than the buttock and spine areas.
Most cases of congenital dermal
melanocytosis do not need to be seen by a doctor, unless there is some doubt as to the type of mark your child has. If the spots are particularly large, growing or located near the mouth, then these should be reviewed by a paediatrician or paediatric dermatologist (skin
How can I tell if it's a bruise or a congenital dermal melanocytosis?
Congenital dermal melanocytosis and bruises do look very similar, and
the birthmarks are often mistaken for bruises. However, they are different in a
few ways. Bruises change colour, size and shape over the course of just a few
days, while congenital dermal melanocytosis stay the same for many years. Also, congenital dermal melanocytosis are not painful when touched. Congenital dermal melanocytosis are present from
What can I do if my child's congenital dermal melanocytosis is very
prominent and is causing them embarrassment? Is laser treatment an option?
We do not recommend any treatment for congenital dermal melanocytosis, as it is unnecessary because the birthmarks will fade over time on
their own. Treatment, such as laser therapy, may cause side effects, including
infection and scarring.
Developed by The Royal Children's Hospital Dermatology department. We acknowledge the input of RCH consumers and carers.
Reviewed August 2020.
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