A Flickr user has uploaded photos of what it looks and sounds (from the description) like cold urticaria.
Testing procedures for diagnosis of physical urticarias depend on the cause (stimulus):
- Dermographism: Stroking with narrow object, e.g. a tongue depressor
- Cold urticaria: ice cube test
- Heat urticaria: test tube water at 44°C (111°F)
- Pressure urticaria: Sandbag test or a bag with heavy books (Middleton's Allergy textbook, 2 volumes)
- Vibratory urticaria: vibration with laboratory vortex for four minutes
- Cholinergic urticaria: exercise for 15-20 minutes or leg immersion in 44°C (111°F) bath
- Aquagenic urticaria: challenge with tap water at various temperatures
Related reading:
Urticaria: A Short Review. V. Dimov. Clinical Notes in Allergy and Immunology.
Image: Cold-Induced Urticaria http://twitpic.com/e8lh2 - via @MatthewBowdish
Idiopathic Cold Urticaria. Consultant. Vol. 45 No. 13, November 1, 2005.
"Young mother must wrap up all year round because she is allergic to the cold"http://goo.gl/w25WB - Cold urticaria in Daily Mail.