Mongolian blue spots are a type of birthmark. They are flat blue or blue/grey spots with an irregular shape that commonly appear at birth or soon after. They may also be called congenital dermal melanocytosis or dermal melanocytosis. Mongolian blue spots are most common at the base of the spine, on the buttocks, and back. They also can appear as high as the shoulders or elsewhere on the body. They are common among darker skinned races, such as people of Asian, East Indian and African descent.