What Causes Oval Shaped White Patches On Torso?

I get two oval shaped rough skin patches on the left and right sides of my torso just below the ribs. These patches are slightly brown in color; they do not itch and are not painful. Each of these areas is a little smaller than a dime. I do not have dry skin anywhere else on my torso. I am 57 years of age; I have spent little time in the sun. I live in the U.S. Would you have any idea what this could be?