What's The Diagnosis #9


A patient presents with an itchy rash to the elbow that started a week prior to presentation. After initially becoming red, the rash developed small blisters then the blisters ruptured, leaving small sores. There is no warmth or fluctuance to the area.  The patient saw his primary care physician 5 days ago and was prescribed topical steroids which had no effect on the rash. He also notes that he has been having diarrhea and stomach cramping lately. WBC count and sed rate are normal.

What is the diagnosis, how is it treated, and what other disease is it associated with?

I’ll post the answer below the picture on Friday.


Answer: Dermatitis Herpetiformis
Kudos to anon for the perfect answer.
Dermatitis herpetiformis is associated with celiac disease. In fact, some clinicians assert that a diagnosis of dermatitis herpetiformis can be used as a “backdoor diagnosis” to celiac disease.
DH occurs most commonly in the extensor surfaces of the joints, on the buttocks, and on the back of the neck, but can occur anywhere on the body. It is often misdiagnosed, being confused with drug eruptions, contact dermatitis, dishydrotic eczema, and even scabies.
DH is diagnosed by skin biopsy, but multiple biopsies must be taken from diseased and healthy skin as at least one biopsy must show IgA deposits in the dermal layers under immunofluorescence in order to confirm the diagnosis.
Long-term treatment is a gluten-free diet, but dapsone (a drug used to treat leprosy – more in-depth information here) may be used to treat the rash in resistant cases or in flares.

Read more about dermatitis herpetiformis at the Celiac Sprue Association, eMedicine.com and Medline Plus.



  1. Looks like the gout sores my father developed when he was still drinking regularly a few years ago. I remember steroids didn’t do much for them either, but he eventually had them in more than just one joint. I’m not a doc so I’m probably not in the ballpark, but it never hurts to take a swing.

  2. Doesn’t have any tophi by the looks, no other arthropathy means prolly not rheumatoid nodules, maybe a infectious arthritis with skin signs if the joint is also involved? Could also be pyoderma gangrenousum I suppose, it is strongly associated with IBD/IBS. Hypercalcaemia could cause GI/abdo signs with cutaneous deposits, there’d probably be a few more symptoms from it though…

  3. If I had to guess I’d go with a herpes rash…which explains the diarrhea and cramps as well. I’d rule out a toxin because it’s been 5 days and poison ivy cause steroids did nothing. If I were stretching I’d maybe guess pruritus, but the pictures I’m seeing aren’t very close. Of course I’m an engineer (nearly) and not an MD, otherwise I’d pop over to the med library and start flipping through some rash picture books *thumbs up*

  4. Poison Ivy, though you do not mention that it itches. I get it about 5 times a year and that looks just like it. Treatment would be to advise the patient to not drop onto all fours in the back yard.

    • Damn,I didn’t see this. Dimwitted ingestion of said plant would lead to the GI symptoms or they could be unrelated. Not that I didn’t take that bet when I was young.

  5. It’s so interesting to me how quickly a random person on the internet can guess something I had for decades without a proper diagnosis.

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