I have developed a mark on the glans of my penis. It is about a quarter of an inch across, irregularly shaped, whiter than the surrounding tissue, and with a distinctive brown border. There is no pain or soreness of any kind. I do not know how long it has been there, but at least for the past month there has been no change that I can see in its size or texture. If I have an erection the flow of blood almost makes it disappear. I am 73 years old, and caucasian. The last time I had any contact with a woman was a year ago. Any comments?