I have. For me, I am sensitive to the high salt concentration. And twice I received bumps from being bitten by bristleworms. And in Mexico (obviously not directly related to my saltwater tank) I broke out in hives due to the seaweed in the water.
That happened to me once. I got a poison ivy-like rash on my finger, about 2" long and .75" wide. Since I got it from my tank, I figured that I should have it checked out. I went to my dermatologist, who took a scraping and prescribed bactroban cream, an antibiotic. It disappeared within hours after I put on the cream, so I am assuming that it had to have been bacterial in origin.
You could be sensitive to the salt, could be allergic to something in the tank- there's no way to really tell. Best to just be cautious and wear gloves.
my skin get really itchy in the dead sea, and couldnt take it. But I have never had any issues in my tank, I have touched my RBTA and every kind of LPS/Softy, never a problem.
But now I often wear reef sleeves from thefiltergiys.biz just to be safe.
what ever it is its not a joke and things like that have to be looked at by a doctor .
I pinched my finger on live rock ones and when i woke up the next day my hand was huge all blue and purple no finger movemet i ran to the emergency room ! got a bunch of shots, and the pain ! and i had to stay there the whole day