A weird, itchy rash is linked to the keto diet—but no one knows why

A 20-year old man in Taiwan went to a dermatology clinic for a strange rash that had developed across his shoulders and chest. The raised, red, and itchy condition had been bothering him for a full month. By this point, he had also developed patches of pigmented skin interlaced with the red rash.

According to a case report in the New England Journal of Medicine, a skin biopsy showed swelling between his skin cells and inflammation around blood vessels, but testing came up negative for other common signs of skin conditions...