I'm going to a new dermatologist tomorrow to have a bump looked at. I really hope that my BP is not taken. I have bad white coat syndrome and really don't feel like convincing another doctor that this is truly the case and not hypertension (my family doctor is well aware of my long history of this-since I was in high school-history of high systolic readings before an exam, and normal (120) systolic after the exam).

Could I just explain that and refuse to let them take it?

I don't know, but I've never had a dermatologist bother with BP.