I noticed very similar (if not identical) patches on my inner thigh one week ago. I have two one one side, two on the other. The skin surface seems normal, but the original pinkiness has changed to brown. They haven´t grown yet, nor have other appeared, yet, but I don´t like the look of them.
From what i´ve read on the internet they would seem to be good candidates for one of two rare skin cancers. I went to see my local doctor, and he seemed totaly unconcerned and gave me a cream to apply, which after just 2 days has done nothing.
I can´t find any type of skin fungus that would cause these, and the skin surface is normal, which might rule our eczema. I´ll let you know if I find anything useful. I have a web site which might be useful, with images of similar rashes.