DH can come & go gluten eating or gluten free. But if your mom is getting the rash & it's dh then one day it will likely flare very badly. If it's dh then she has celiac disease & needs to go gluten free. It can take up to 2 years (or more) gluten-free for the antibodies in the skin which are what causes the rash to get out of the skin so it no longer flares. Ppl with dh tend not to have the GI symptoms, instead the immune system attacks the skin. Or they have fewer, less sever GI symptoms. Since you have been dx'd celiac then there is a good chance that what your mom has is dh. A 50/50 chance or better depending where the genes came from you see?
Here are some links with photos of dh:
DH can take many forms so if your mom's doesn't look like one of the photos it doesn't mean it isn't dh. The hallmarks are the intense itching, especially at night. An itch like you've never known in your life! It often presents bilaterally, ie: the same places on opposite sides of the body. It stings, burns, itches. There may be water blisters.
She can get a biopsy but there is a false neg. rate of 37% even when a really good dermatologist who is experienced in dh biopsy does it. Also she has to continue eating gluten until the biopsy or it will be negative. If she's been on any steroid creams or pills in the 2 months prior to the biopsy then it will turn up negative.
OR, she can just start eating gluten free.
This info. will get you started. Talk to your mom. Ask questions of us anytime. Invite your mom to the site & she can ask questions. We are here to help.
Here is the link to the dh forum: