Rashes are tough to figure out. Everything from changing your to wearing an itchy sweater to skin conditions like eczema and poison ivy to a food allergy can cause one. So dermatologists have their work cut out for them when someone comes through their doors with a mysterious rash.
A 29-year-old man went to a dermatology clinic complaining of an itchy, inflamed, and scaly rash on his back—and you can see the alarming photos in today’s issue of the New England Journal of Medicine. The authors note that he had had the rash two years earlier but hadn’t gone to see a doctor until now.
The first thing doctors do is take a patient’s medical history, in order to begin to go down the right path for a potential diagnosis. This patient suffered from eczema as a child, as well as seasonal allergies. Certain medications can cause rashes, but, as the authors note, he wasn’t taking anything.
Next up was a physical exam. More than 90% of his body had an inflamed, violet-hued plaque (a patch of thick, scaly skin), as shown in the photo below. On the right, an area near his shoulder blade that wasn’t affected gives you an idea of just how widespread this rash was.
Generally, say the authors, these symptoms could point to possible diagnoses including erythrodermic psoriasis (an inflammatory form of psoriasis that affects most of the body, according to the National Psoriasis Foundation), (often affecting the scalp, causing dandruff), and pityriasis rubra pilaris (a group of rare diseases that cause red, scaly patches that spread over the whole body).
After a skin biopsy from two places on his back, the doctors landed on their diagnosis: erythrodermic psoriasis. This rare type of the skin condition only affects 3% of people with psoriasis. While the case study doesn’t mention the patient’s comfort level, the condition can be painful and very, very itchy. Along with redness, skin can shed in large “sheets.” It may also cause protein and fluid loss and affect the body’s ability to regulate its temperature—dangerous side effects that can actually be life-threatening. (And remember, this patient waited two years to seek treatment.)
It’s one thing to treat the rash, but often, the skin reveals a systemic disease simmering beneath the surface. Doctors look for potential underlying causes like infections, alcoholism, severe sunburns, or emotional stress. In the NEJM case, an HIV test came back positive. The patient was then given antiretroviral drugs, medications that stop the progression of HIV, and a topical corticosteroid to treat the rash itself. After three months, his skin cleared.
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