I have a similar blue bump on my back. It doesn't look anything like the skin cancer pictures but it is still worying me. I am going to get it checked out tomorrow.

I have one of those blue lumps as well on the top of my rear...it seems to have been there for about 8 years now and it has turned from a small light blue dot of about 1mm in size to a teal/blue dot in 2mm in size over the past 8 years.