Mongolian blue spots, also known as slate gray nevus, are a type of pigmented birthmark. These marks are flat and blue-gray in color, and typically appear on the buttocks or lower back. They are generally present at birth or soon after. Mongolian blue spots are common in people with dark skin, particularly those of African, East Indian, or Asian descent.
These pigmented birthmarks are noncancerous and present no danger to your health. However, your pediatrician should examine the marks to confirm the diagnosis.
There is no recommended treatment for these birthmarks, and they often fade before the child reaches adolescence.
Mongolian blue spots are birthmarks, but because of their color, they can be mistaken for bruises. The birthmarks are:
- flat against the skin, with a normal skin texture
- blue or blue-gray in color
- usually between two and eight centimeters wide
- of an irregular shape with unclear edges
- usually present at birth or soon after
- anywhere on the body, but usually located on the buttocks or lower back, and less commonly, on the arms or trunk
The cause of these birthmarks is unknown. However, the color of pigmented birthmarks is determined by the amount of melanin (the substance responsible for skin color) you have. Therefore, you are more likely to have Mongolian blue spots if you have darker skin.
Mongolian blue spots are harmless. If your child appears to have Mongolian blue spots, make sure that your pediatrician examines the spots at your baby’s first checkup. A physician can diagnose Mongolian blue spots based on their appearance.
These spots are noncancerous and are not indicative of any disease or disorder. There is no need for medical intervention. In many cases, the spots fade over time and are gone by the time the child becomes a teenager.