Possible skin cancer

I just noticed a lesion on the back of my left arm yesterday.  I don't recall getting scratched there or anything like that to cause a scab.  I took a picture of it and I am a little concerned that it could be cancer.  The picture is attached.  

[midb]

It may be OK.  I have a spot very similar to this one.  The best is to get a full skin exam by a dermatologist to exam this spot and others.  Let us know what you find out or if you have any questions.