If you have Dermatitis herpetiformis(DH) that is celiac disease. No, not everyone with CD get DH. Other skin problems can be associated with gluten - psoriasis, eczema, dry skin and hives. Here is an article on cutaneous manifestations of celiac disease http://www.wjgnet.com/1007-9327/12/843.asp

The Gluten File has some references to skin disease and gluten http://jccglutenfree.googlepages.com/ (I did not see the above article in TGF, but it may be there too)

I had a bumpy, non itchy rask on my back and arms. I also had strange red bumps on the soles of my feet. All of this disappeared with a GF diet.

If Iodine brings out the rash, that would make it more like DH. I have not heard how long the biopsy would be positive once the lesions heal.

Sorry the biopsy hurt. Let us know the results.
Anne