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Skin Care and Diseases

Rash on back



My girlfriend has a rash on her back that is red but when I looked closer it appeared as hundreds of little clear bumps. The doctor told us it was poison ivy but we have not been around any shrubs to contact it and how`d it get on her back we thought. Was wondering if you perhaps had a different diagnosis? It is a painful rash and we`re applying cream to treat it.


It is difficult for me to give you a name for a differential diagnosis on something like this.  I don't know the duration; I don't know other symptoms; and truly don't have an idea of the texture that we are talking about.  I would assume that your physician saw a pattern of streaks with blisters along the course of them, having made the diagnosis of poison ivy; or there was a history of walking through smoke coming from poison ivy vines which can produce a diffuse red eruption that has small blisters in it.  The eruption should occur within 48 to 96 hours after the exposure, and if untreated with systemic steroids the process often lasts 21 to 28 days and then resolves if there is no further exposure. 

I do not know the character of the vesicles, whether they are umbilicated and smaller which might suggest herpes simplex along the nerve trunk or herpes zoster along the nerve trunk. Those are usually quite tender and painful, are usually segmental, and frequently just on one side.  In the case of shingles/herpes zoster/chicken pox infection there may be other blistering lesions that are comfortable that occur elsewhere on the body.  I doubt from this description that any of the immunobullous disorders are an issue here.

So, in summary, you see it is difficult to pinpoint the process.  It would be to your distinct advantage to see your board certified dermatologist so that a very accurate diagnosis can be established, either from the clinical form and pattern and/or a biopsy of the lesion to make a more definitive diagnosis.

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Response by:

Charles L Heaton, MD
College of Medicine
University of Cincinnati