“She has a history of a blood clot in her leg as well as fainting episodes culminating in a fall and concussion in 2012. This was followed by a blood clot outside her brain known as a Transverse Sinus Thrombosis.”
http://www.washingtontimes.com/news/2015/apr/28/marc-siegel-hillary-clintons-health-and-our-right-/
Thanks for the link, Joe. While the article and comments were interesting, even the blurb in your quote do not address anything that would leave a scar on her neck... if indeed that is what it is.