Some of this derm stuff is quite annoying (specifically the vocab). Im guessing on the real deal they describe the word rather then say the word, like describe what acantholysis is, any pointers?
I could never tell the difference between pemphigus vulgaris and bullous pemphigoid, even after re-reading FA.
Here's the easiest way to tell them apart (assuming you're not given IF results): pemphigus vulgaris affects the oral mucosa. Bullous pemphigus does not.
They always give you that if they don't give you the IF, and remembering acantholysis and Nikolsky's sign becomes secondary.
Pemphigus vulgaris - Autoimmune disorder with IgG directed at the desmosomes. This results in acantholysis (of the stratum spinosum layer I believe) and a positive Nikolsky sign (press on the bullae and it will spread out)
Bullous pemphigoid - Has IgG directed against the hemidesmosomes. This results in separation of the dermis from the epidermis (as compared to an intraepidermal separation in p. vulgaris). Since the separation occurs below the epidermis there is no Nikolsky sign.
I disagree with your def of nikolsky sign. it is bleeding/ sloughing of cells on finger pressure. i do think just from a pathophys point of view that pressing on a bullae in BP will spread the bullous because it will separate more cells from the basement membrane.