This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
A 85 year old woman with Nikolsky sign–ve, blisters on thigh & trunk, lesions come on & off. What is the cause – 
Select and explain. 
A. Pemphigus vulgaris, B. Pemphigoid, C. Lichen planus, D. Dermatitis herpetiformis
B: Pemphigoid
Answer: B: Pemphigoid 
Explanation: In this question :-


Age → 85 year
Blisters on lower body (thigh & trunk)
Nikolsky's sign negative


Amongst the given options only pemphigoid (bullous pemphigoid) full fills these criteria.