You are the NNP called to examine a term newborn male roomin…

You are the NNP called to examine a term newborn male rooming in with his mother.  The post-partum nurse discovered an irregularly bordered, flat, pink macule on the nape of the his neck.  Based on this description and your knowledge that 40% of all newborns have this type of skin lesion, you would add which of the following to your differential diagnosis list?