Is it necessary to test for all tree nuts when a patient presents with IgE mediated symptoms to an isolated tree nut?

Having an allergy to a specific tree nut does not mean a patient will be allergic to others, but there are some that are cross-reactive, and it may be worthwhile testing for the cross-reactive tree nut as opposed to testing for all. For example, if the patient had a reaction to cashew, testing for pistachio would be appropriate, and if they had a reaction to walnut, testing for pecan would be appropriate. It would be important to do a detailed history of other tree nut consumption before conside...

I assume every patient allergic to cashew is allergic to pistachio and warn them that they are at risk. Most patients allergic to walnuts will, in my experience, be allergic to cashews, but it may be worth testing. Almond is the least likely to react, and an in-office challenge is often worthwhile, as a low level of skin test or RAST reactivity may not be clinically relevant.