In other cases, anaphylaxis may be difficult to diagnose. Some conditions may share some clinical features of
anaphylaxis, such as loss of consciousness and hypotension (as in vasovagal syncope) or generalized urticaria
(seen in scombroid fish poisoning or systemic mastocytosis). These syndromes must be ruled out before a
definitive diagnosis can be made.

SM as a syndrome thay should be told that SM can have venom IGE aswell

http://www.aafatexas.org/docs/Anaphylaxis%20Primer%20for%20Healthcare%20Professi...