A<unk> , also known as slate grey nevus or congenital dermal melanocytosis, is a benign, flat, congenital birthmark with wavy borders and an irregular shape. In 1883, it was described and named after<unk> s by Erwin Bälz, a German anthropologist based in Japan, who erroneously believed it to be most prevalent among his<unk>  patients. It normally disappears three to five years after birth and almost always by puberty. The most common color is blue, although they can be blue-gray, blue-black or deep brown.
Mongolian spot
Fuchs spot
Forchheimer spots
Bier spots
Fordyce spots
Elschnig spots
Koplik's spots
Bitot's spots