I have battled with this for ages now and finally given up... 

I have V4 in a pose sitting on some steps. Her head is twisted -8 degrees and her neck is twisted -10 deg, side-a-side -15 deg and bend -10 degrees (I have altered these all quite a bit with no effect). Her cheek shows distinct banding when rendered. nothing shows in Preview mode. I removed the skin texture.. her face looks fine... I rendered and the creases are still there.

See attached pic. Left hand pic is the problem as described, Middle is Preview mode with the skin removed (it looks fine with the skin texture applied too). Right hand pic is the middle pic rendered... the creases show up.

So, in desperation, what is happening anyone please?? and how can I fix it?

Thanks in advance!