[Allergic seasonal rhinoconjunctivitis without indigenous pollen sensitization: the example of the Arizona cypress].

A 37-year old man from Lithuania presented with the typical symptoms of allergic rhinoconjunctivitis that appeared in spring this and the year preceding presentation. Skin prick tests for aeroallergens indigenous in Switzerland were all negative. A detailed history revealed that the patient was working in a building of a United Nation's agency surrounded by a park with numerous cypresses of Arizona trees. A skin prick test for pollens from Cupressus arizona was strongly positive, supporting the diagnosis of allergic rhinoconjunctivitis to pollens from this tree. Allergy to pollens from C. arizona is a widely prevalent as winter pollinosis in subtropical and Mediterranean areas but is exceptional in the continental and alpine climates of Switzerland. Five cases of C. arizona pollinosis have been diagnosed in the last 3 years in Geneva. It is notoriously difficult to diagnose cypressus pollen allergy, mainly because of the poor quality of in vivo and in vitro available tests. Horticulture with non-indigenous plants is responsible for pollinosis from C. arizona in Switzerland. The specialists in countries in which pollinosis from C. arizona is not endemic, need to be aware of arboriculture with non-indigenous plants, as well as the possibility of allergy to C. arizona.