Strange spots on inner thighs

I dont know if this is related to me being male or not, but here goes. Ever since I was a young teenager (I'm now 31) I've had discoloration on the insides of my upper thighs just about the size of my testicles and in that location, except on my inside thigh. These discolored spots are not exactly circular, sorta odd-shaped. I remember they grew when i first got them to about the size they are now - testicle size and have stayed that size ever since. Sometimes the color fades, sometimes it gets darker and turns even a bit reddish. It doesn't hurt, the skin feels smooth and normal. Anyway I've never really had a reason to see a doctor for this because as far as I know it hasn't caused me any problems.

Does anyone know what these might be symptoms of if anything?