[Frequency of the so-called "apple allergy" ("apple contact urticaria syndrome") in patients with birch pollinosis].

Rhinitis, itching and tingling and other mild reactions on the oropharyngeal mucosa are the most common complaints after eating raw apples (in about 30% of patients with hypersensitivity to birch pollen). Angioedema, urticaria and shock are rare, but must be noticed. On the basis of three case reports we are illustrating the difficulties of reliable test procedures. 49 patients have been examined by means of "scratch-chamber" test method, RAST and peroral provocation tests. The nature of the actual allergens (lectins?) is still unknown. The term "contact urticaria syndrome" should be used.