Do you perform a bone marrow biopsy in all patients with grade 5 anaphylaxis to stinging insects and negative workup for HAT, MCAS, c-KIT?  

Before saying that bone marrow biopsy is the next step (which it is), we must be certain that we are correctly assessing the situation. Was there documented hypotensive shock (and not just subjective light-headedness or brief vasovagal syncope? Were there other objective signs like urticaria (althou...