Hi,
Just to put your mind at rest, I had really severe Psoriasis all the time i was at uni. When i came out after 3 years, it was at it's worse which was about the same time i went for my I nitial Class One.
I thought they'd make a big deal about it but no-one mentioned anything, and i've had 3 renewals since then!
So no, i really don't think it's a problem.
Hope that helps.
Chile
p.s don't scratch it!!!