I believe it is a fungal infection. I had this on my leg when I was a kid !! They reckon that I might have slid in some dogs poop when I was playing football and picked it up from that ( I was quite young mind - so they could really have told me anything !!!!). I remember having to put some stinking ointment on it - smelt worse than the aforementioned doggy poop !!
yes it is a fungal infection I had it on the palm of my hand once and I got it from a hedgehog! (I have rescue hedgehogs sometimes). it started as small blisters which then broke and left very dead skin behind - it spread in a ring across my hand and I lost several layers of skin. It is treated with an anti fungal cream.
Needless to say I always wear gloves when handling hedgehogs now!
Yeah, I got it from my cat once - it was a Saturday when I noticed ithe red ring on my face so Doctors closed. Bought some anti-fungal cream used to treat athlete's foot and started using that until I could get to the doctors the next week. He just said to carry on using that!!