What is the color and appearance of a Mongolian spot?

The color and appearance of a Mongolian spot are distinctly characterized by their flat and gray-blue coloration. These spots, which are a type of congenital dermal melanocytosis, are typically seen in newborns, particularly those of Asian, African, or Hispanic descent. A Mongolian spot often presents as a blue or bluish-gray mark on the lower back or buttocks, and it is flat to the touch.

This presentation is significant in clinical practice as it helps differentiate these benign birthmarks from bruises which may indicate trauma or abuse. The smooth and flat nature—without any elevation or texture—helps to confirm the diagnosis of a Mongolian spot. Other color variations or elevations would not align with the standard characteristics expected for this type of skin marking.