Peanut/ Peanut Butter allergies?

Is it possible to be allergic to peanut butter but not peanuts?
I was watching my nephew yesterday and had to take him to the emergency room because apparently he had an allergic reaction to peanut butter. I gave him one of those cheese crackers with the peanut butter in the middle (with the peanut butter scraped off).
My sister is going to make him an appointment with a specialist for an allergy test.
I just thought this was strange because my sister feeds him boiled peanuts.
Just to be clear if it (boiled peanuts) makes any difference we live in Maryland so the boiled peanuts my nephew eats are made by my sister. She buys them and boils them herself.

There may be a certain component in peanut butter that makes him allergic to it... it may not actually be merely from the peanut, because as you've said he's not allergic to peanuts but to peanut butter instead.....

Hope it was helpful.........

He could be allergic to a certain type of peanuts.