“Did these hives come from my truck accident or didn't they?” asked a twenty-eight-year-old man. Five weeks before the hives appeared he had almost been killed in a truck accident. Now, a year later, the hives continued. We did not know the answer to his question, but were eager to find out. His hives were the most unusual we had ever seen. They were small red mosquito bite-like swellings, but each was surrounded by a remarkable halo of white blanched skin.

We were familiar with cholinergic urticaria, small hives resulting from heat, exercise, or emotional stress. But, these hives have halos of redness, not blanching. They result from an abnormal sensitivity to the neurotransmitter, acetylcholine. Injection of this chemical into the skin exactly reproduces the small hives with red circles. When patients say their hives are the result of “nerves,” we are usually skeptical, except for this, the only authentic example. For most patients hives are not due to nerves, but result from an allergic response to any one of a thousand allergens. Our patient did not have cholinergic urticaria. He had white halo hives, not the red halo-type due to acetylcholine release from stress, heat, or exercise.

Yet, could his hives also be due to nerves, perhaps with a different neurotransmitter? No one had ever described such hives, yet his history clearly implicated “nerves” as a possibility. His truck accident left him with a morbid fear of driving.