<<Disclaimer:  Verify this information before applying it to your situation.>>

I have put a post on this subject before to the list so search the archives.
The GIG of seattle have a very nice synopsis on the topic that they
give/send to health professionals and They may give to you too.
I am not sure if everyone with a confirmed case of DH needs to have a
biopsy of the intestine.
Certainly a definite postive biopsy of the skin confirms gluten
sensitivity of the individual.
 If The person adheres to a strict gluten free
diet to manage their skin condition then It is not always necessary to
biopsy the intestine.
The biopsy can provide useful additional information, but if it to
persaude anwilling patient/dermatologist that a diet if beneficial then a
careful explanation of the scientiific information should suffice to
persuade most.  The eventual should be to control the skin condition with
the GFD alone.  There is no doubt that the drugs used dapsone and sulfa
drugs are very useful to get the itch under control but they can have
side effects and do not benefit the intestinal damage that often
co-exists.
Joe Murray
disclaimer( not medical advice)