I'm here because I just found this same type of rash on my back. My boyfriend says it was there yesterday, too, but I don't know when it started. I'm 32, female, no history of eczema. I've had weird rash patterns before but not like this.

I do have a chair with a diamond back pattern, so it could be that, but I don't understand how that could have done it unless I had my bare skin against it. The rash is in the middle of my back, always covered by a shirt.

Also, if it was the chair, why are the red spots showing up only in the negative space of the grid? The center of the diamond, not the grid part, is red. You'd think it would be the other way around if it was a reaction. And I sit in those chairs often and have never seen this before. I don't even think the grid has the same dimensions as the one on the chair.

I can't believe there isn't more information on this, since other people have experienced it too. I haven't yet seen a convincing possible diagnosis from a medical professional. I wonder if it's an autoimmune type thing.