"Blisters, Bullae, and Body Warnings: What’s Your Skin Trying to Say? A young woman wrote in asking about bullous pemphigoid, a blistering skin condition that often shows up in body creases—between the toes, under the arms or breasts, inner elbows, etc. What’s the cause? “Etiology unknown.” “Autoimmune.” Translation: We don’t know. But here’s the thing—your body never does something without a reason. In my practice, I don’t buy the idea that the immune system randomly turns on you. It’s not atta