re-occuring doughnut shaped hive(?)

I have a strange hive that is re-occuring on the EXACT same spot on the front of my neck.  It is almost exactly the same size and shape of a lifesaver candy, raised skin in a nearly perfect cirle with unaffected circular center.  It comes on very suddenly and itches only as it is just appearing.  Within a few minutes of its appearance, it slowly begins to fade away and is gone within
1/2-1 hour.  

It first appeared about 9 months ago.  Within this time period it has only shown up about 8 times, but 5 of them have been within the last 2 months.  Each time the hive occurs it is slightly larger and more prominent than the time before.

I have not been able to determine a trigger.  Thought for a short time that it was a reaction to advil.  In the last 6 months I have taken advil four times for headaches and exercise induced muscle pain in the neck.  Each time, the hive occured within a few hours after taking the advil.  However before and since then the rash has occured with no relation to advil whatsoever.  

Other than when the hive occurs there is absolutely nothing unusual about that spot on my neck and I am very healthy.

Thanks
Jami

[Alan Rockoff, MD]

The only condition this remonds me of is called a fixed drug eruption.  This refers to an allergic reaction which affects not the whole body but one spot.  Finding the trigger can take detective work, sinnce no allergy test is useful, though a skin biopsy may support the overall diagnosis.  Advil can cause such a thing--perhaps you are taking some other medication which contains ibuprofen?  You should discuss this with your dermatologist, if you have one.  A photograph of the hive in full bloom may help.

In any case, allergic or systemic causes seem unlikely.

Best.

Dr. Rockoff