I was thinking something along these lines but didn't say anything. My husband has vitiligo, which he's only had a few years. He also has type 1 diabetes which has been for 20ish years now. I think (working on diagnosis) that he also either has celiac or crohn's. (God... let it be celiac, far less scary!) I've noticed when he gets bad "flares" with his intestinal problems he also develops more "spots." So while it isn't specifically linked to a lot of things, I have no doubt that when his AI system gets all wonky that it's what is making him splotchy too.
I have a fun set of diseases myself, AI and otherwise. And while one isn't linked to any specific AI disease, it is common acceptance that it is far more common among people with one or more AI diseases no matter what they are. I know that some links are specifically established, and that's great. But I don't think it is fair to discount that AI diseases in general tend to be linked and cluster, regardless of what they are.
Yup...I agree, Addy! The key is to tame down the immune response and diet is always a good, first start. I think any one with any AI disease should be tested for Celiac.....simple little blood test! If that comes back negative and the immune problems are ramping up, I would just do a dietary trial for awhile. Can't hurt to eat gluten free