It certainly sounds to me like masto!!!!!!!!!!!!!!   I´ve had reactions like this before and a regular dysautonomic response would not cause flushing.   I have been seen with this very rashing as well, a very white background with those red splotches - no itching.  

This also sounds like a hypertensive masto reaction and I say that because I too get hypertensive and I also have hypertensive POTs when I´m doing a lot of reacting.   I´ve had my pressure hit the roof at 230/110 just cause I had to stand still waiting for 5 minutes.   I suggest your doctor run a 24hr urine metheyl-histamine, 24hr urine prostaglandin D2 and also run several typtases to see what is going on.   To have the one test come in elevated is not enough but it is indicative to masto yes.  

Run this by your doctor and if you are wanting, I can send you some articles which will help you and your doctor.   Send me a PM with your email address and what we are talking about here and I´ll be happy to send you related articles.



I hope this helps!!

Lisa

Devils advocate is fine! Haha I am hoping its not MCAS too. I definitely have dysautonomia, diagnosed at Vanderbilt and by an autonomic neurologist where I am now. They dont even know what kind of dysautonomia to call it because its like POTS but different in some testing ways. However, we can't find a cause other than maybe a viral attack on my system. My system is super reactive to many things. The past like 9 months I have been flushing in my face with smells or sunlight or heat or anything that stimulates me like that. This is the first time that has actually caused a rash. I have had a reaction to contrast dye a couple of years ago that required two doses of IV Benadryl to stop. Also had a reaction to lidocaine (it didnt even have epinepherine in it like it usually does so they think it was in fact allergic reaction) I just had a reaction to a food smell that came into our apartment. Flushing, increased HR, diarrhea, increased BP. So I honestly don't know if its my overreactive sympathetic nervous system just being stimulated by strong smells or a reaction to the smell itself.

I am forbidden to take antihistamines unless its an emergency by my autonomic neurologist. Antihistamines can affect your parasympathetic nervous system and mine is so messed up right now antihistamines could cause deadly heart arrhythmias for me. So I have Benadryl in my medicine bag in case of major horrible reaction but other than that I cannot take them. Even Claritin, Zyrtec etc are off limits.

During my rash in the hospital I was coherent enough to get my nurse to call the doctor and order a urine N methylhistamine test which he did and we got samples immediately after my episode. Waiting on those results still. I was having too much brain fog to remember tryptase and prostaglandins too. Haha. Thanks for the responses. Hopefully this will help some and maybe can illicit more advice.