Minimal Spinal Dysraphism vs. Mongolian Spots
Left picture: Although this toddler exhibits a spot on the left side between the buttocks analogously to the one over the sacrum, it is an indication of a minimal spinal dysraphism until proven otherwise by negative additional examinations, because a nevus with such a localization is a frequent combined anomaly of minimal spinal dysraphism. Right picture: On the contralateral picture of the 11-month-old infant a blue spot is present, recognizable mainly in the picture in the middle on the same side of presentation, which was performed 4 months later. The shape and the aspect which does not change in the course of time do not support a hematoma following battered child syndrome; the incidental lesion may look like in the picture at the bottom of the same side of presentation. Mongolian spots lie over the sacrum, on the lower back, or on the buttocks, and are grey-brown or dark-blue; they are caused by a melanocystic nevus and turn pale by the time of puberty.
Left picture: Over the sacrum a dark-red spot is visible with irregularly serrated limits. Right picture: At a comparable site a dark-blue spot is recognizable on the left side of the midline, and in addition, a larger spot of the same color in the upper part of the right buttock in the same patient, visible at the bottom of the picture.