Infants whose buttocks are greenish in color are mostly considered to be due to Mongolian spots, which may be caused by heredity. Mongolian spots belong to a congenital benign gray-blue spots, which usually appear at birth and can be found on the buttocks and lumbosacral region. The plaques are round, oval, or square in shape, and most of them fade away on their own before nap time, while a few patients continue to have them into adulthood. Usually, Mongolian spots have no adverse effects on the body and there is no need to worry. It is mainly due to genetic factors, and is caused by the migration of melanocytes from the neural crest to the epidermis during the embryonic period, thus staying in the deeper part of the dermis. When the pigment particles are located deeper in the dermis, when through the skin can show a special grayish blue, blue. Infant buttocks are cyan, there may be other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.