<human>: Approximately 6 years ago I had a minor dermatological procedure - I THINK I had a very small hemangioma removed from my chest, but it was such a minor thing that I don't really even remember what exactly the thing was and how exactly it was removed.

The doctor injected some kind of topical anesthetic before hand. Within 4-6 hours I had major hives over my entire body, particularly my torso, neck, and scalp. I have only had hives one other time, so my family doctor was fairly sure it was related to the injection. The hives persisted for about 3 days even with enormous doses of Benadryl and H2 blockers. 

I assumed that the injection was lidocaine, but my dentist recently cast doubt on that assumption and said lidocaine allergy is extremely rare. He thought it was probably benzocaine. 

I need to know this because I am having a dental procedure done tomorrow. It only just occurred to me that the oral surgeon might be uncomfortable using anesthetic that I might be allergic to. 

I have never had any other kind of topical anesthetic. My grandmother was dangerously allergic to novacaine. I have no idea if that is even related to either of these drugs.

Can you give me the gist of the text in a nutshell?
<bot>: What topical anesthetic was probably used 6 years ago when I had a small red skin thing burned off my chest, that caused severe hives?