Need For Endoscopy Following Dh Dx?

Hi all,
I have been dx by skin biopsy this week with DH. My GP is saying I still need to have the endoscopy for intestinal diagnosis and I'm having trouble understanding why. Whether it is poitive or negative, my treatment plan still remains dapsone and gluten-free diet. Do I require an intestinal biopsy to have a 100% conclusive celiac disease dx. Does anyone have any suggestions on this?

Thanks!