Extensive Mongolian Spots in a Hypotonic Infant with GM1 Gangliosidosis.

Mongolian spots (MS), also known as dermal melanocytosis, are the most frequently seen birthmarks and generally present as large, blue or blue-black macules or patches, mostly limited to the lumbosacral region. They are considered as a benign manifestation; however, extensive MS can be a manifestation of certain underlying inborn errors of metabolism including GM1 gangliosidosis.