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: Pathology
A patient comes to u with an ill defined, irregularly shaped gingival erosions which are painful and are of short duration, a few months later skin lesions were also noticed, on histopathological examination Tzanck cells were found, probable diagnosis is: 
Select and explain. 
A. Lichen planus., B. Pemphigus Vulgaris., C. Angioneurotic oedema., D. Behcet syndrome.
B: Pemphigus Vulgaris.
Answer: B: Pemphigus Vulgaris. 
Explanation: Oral manifestations:

Oral lesions common and precede skin lesions by months
Intact bullae are rare; patients usually present with ill-defined, irregularly shaped, gingival, buccal, palatal erosions, which are painful and slow to heal
Erosions extend peripherally with shedding of the epithelium.