What Causes Redness And Itching On Top Of Shoulder?

I have this place on the top of my shoulder that has very slowly increased in size. It is slightly raised and seems to be a bit inflammed on the edges by its reddish appearance. The center contains like a scab like feature. The area is not painful, but it does tend to itch when clothing is worn. I've examined many websites, and it looks like a Keratoacanthoma. How concerned should I be, and will it possibly heal itself as some of the websites have suggested? Also, is it possible to identify by comparing it to other images?