Identification of a new physically induced urticaria: cold-induced cholinergic urticaria.

Four patients with symptoms suggestive of either cold urticaria or a combination of cold and cholinergic urticaria were studied. However, all patients were negative to an ice-cube test or cold-immersion test and had no urticaria after exercise in a warm environment. When each patient was seated in a cold room (4 degree C) for 5 to 15 min, generalized urticaria appeared, consisting of puncture wheals and surrounding erythema as seen in cholinergic urticaria. Two patients had weakly positive methacholine skin tests and the other two had completely negative tests. When serial venous blood samples were obtained to test for mediator release, three of four patients had evidence of histamine release and the time course was similar to that previously reported for patients with cholinergic urticaria. These four cases represent a new syndrome with features suggestive of cold and/or cholinergic urticaria, but the results of all the tests usually utilized to diagnose these conditions were negative. We have called this disorder cold-induced cholinergic urticaria to indicate that it is cold dependent and visually indistinguishable from cholinergic urticaria.