I run a community for people who are allergic to methylisothiazolinone (MI) and a number of people have found themselves misdiagnosed with eczema by dermatologists who don't bother to patch test and look for MI reactions. Hopefully that will change soon, as it was voted Contact Allergen of the Year in 2013, but it's slow to gain public awareness. An MI reaction can mimic eczema, lupus, even ringworm. It forms blisters, scales and crusts on some people. On others, it's like hives. Severe eye swelling or hands peeling is also common. I was personally misdiagnosed at least 4 times after major reactions, even by an allergist! Now that I keep MI out of everything in my house and try to be careful outside in the world, my outbreaks are considerably more manageable and infrequent.