Unfortunately, we never came up with a diagnosis. My dermatologist is sure that it is autoimmune in nature. I have autoimmune antibodies, but they are non-specific. So, the treatment is basically immunosuppressant drugs which are working well. Started at a high dose and now backing it off gradually until we find the minimal effective dose. Need to keep doing blood tests to check for potential side effects, but definitely better than using tons of very high potency steriodal creams.