A 59-year-old man presented with multiple painful ulcers in the oral cavity that had developed over the course of a week. He also noted difficulty swallowing and speaking. Physical examination revealed facial edema, with vesicles and crusted lesions in the perioral and auricular regions. Examination of the oral cavity revealed multiple erythematous ulcers, some covered with a whitish membrane, on the hard and soft palates and the buccal mucosa.

Source : NEJM What would be the likely diagnosis? What would the possible treatment? *This case is from Docplexus Editorial Team for Educational purpose only.