Could be dry skin, dermatitis, even a fungus. What a beautiful shade of gray btw
such a cute kitty.
It doesn't look like the typical ringworm (I'm dealing with one at the moment) however there are no fixed rules. Not always appears in round shape but that's the most common. It doesn't look like ringworm from here but there are a variety of skin problems and different kinds of fungus.
We struggled with alopecia with one of our cats
now my angel. He lost the hair in half on his body and nothing would work. Until my mom used some high quality essencial oils for him. (
Caution: Essencial oils should be avoided on cats, back then she didn't know she thought she was doing the best for him we got
very lucky it worked for him and it didn't damage him. But one should
never try that it could end up intoxicating them)
My point with that is that you should treat properly for a kitteh it or it could keep going further and how the lack of information can put them in danger applying something that may be fatal for them.
Maybe the vet can do some scrape and see it under the microscope to see if it is an infection or not and what kind it is and go from there. There's also scabies (it doesn't look like scabies btw) or it could even be some sort of skin allergy.
Before I started my thread about the fungus I looked on the forums for previous info about skin problems and I found a few. Maybe you'll find something that fits better with the symptoms your kitty is presenting.
I found these websites too:
Types of alopecia:
http://cats.about.com/od/diseasesand...lossincats.htm
By overgrooming too:
http://drbarchas.com/psychogenic_alopecia
More alopecia info:
http://www.petmd.com/cat/conditions/...a#.URWOFPJFu8E
P.S. Your cat's bum looks very presentable and clean. No worries we're all used to see cat's butts in here LOL