For about 4 years, I've had a rash that appears occasionally. The first occurrence was very short lived, and was only on my shins. Now it's appearing every few months. The current breakout started on my shins, and it's worst there, but I also have a few blisters on both elbows/forearms and both knees. My back and scalp also itch like crazy. It finally bothered me enough this time to visit the dermatologist, and he told me it's eczema, and prescribed a steroid cream. I asked him if he thought there was a chance it might be DH. He said no, because if I had DH I would also be having gastric issues, and he pointed out that it doesn't look like I'm having any malabsorption issues. 
He also said DH is a blistering disease. I told him that my sores start out as small blisters, but that I inevitably scratch them open. He clarified that the blisters would be larger with DH, and that I would also have them on my buttocks and hairline.
I'm not going to spend time arguing with a doctor about whether fatties can have DH, because I know they can. This dermatologist is actually VERY well respected in my area, and in the past he quickly diagnosed and treated dishydrotic eczema that was making me miserable. I'm wondering if I should ask him to do a biopsy, or find someone else who hasn't already made up their mind that it's not DH. Anyone have a rec for a dermatologist in the Houston area? I'm not positive that it is DH, but I'm not ready to rule it out without a test. I have a hunch that is is autoimmune related. I have Hashimoto's thyroiditis, and I understand that may cause rashes on its own, and that there is also a high rate people with DH who also have Hashi's.
I just read last night that topical steroids can cause a false positive with the punch biopsy, and unfortunately I've already been treating with a fairly potent steroid cream. I suppose the biopsy could be taken from any new areas that crop up if I avoid using the steroid cream there?
Here are some photos from this morning. The inflammation has gone down a bit over the past few days.
