Image of a slate gray nevus birthmark
Previous Next 4 of 7

A slate gray nevus, previously called mongolian blue spot, is a large, blue-gray birthmark that's sometimes mistaken for a bruise. It's more common in darker skinned babies, especially those of Asian heritage, appearing on the lower back and, less commonly, on the buttocks, legs or arms. This birthmark tends to fade during childhood and requires no treatment.