Review Question - QID 110000

A 55-year-old man presents to the emergency department with painful skin lesions. The patient has had similar lesions for the past several months but states they have worsened recently. He has a past medical history of diabetes, a middle ear infection, and urinary tract infection, which were treated with antibiotics. The patient has allergies to latex and sulfa drugs. He works as a mountain ranger and regularly hikes through forestry. His temperature is 98.4°F (36.9°C), blood pressure is 167/108 mmHg, pulse is 95/min, respirations are 14/min, and oxygen saturation is 98% on room air. Physical exam demonstrates the lesions seen in Figure A which separate and break open when minimal pressure is applied. Oral mucosal erosions are also seen upon inspection of the oropharynx. Which of the following is the most likely diagnosis?