Which finding is characteristic of pemphigus vulgaris?

• A. Vesicular lesions on extensor surfaces without mucosal involvement
• B. Bullae only, no erosions
• C. Positive Nikolsky sign only in skin
• D. Oral mucosal erosions with fragile bullae and a positive Nikolsky sign

Answer: (D)

Pemphigus vulgaris is an autoimmune blistering disease where antibodies attack desmosomes between epidermal cells, leading to acantholysis and loss of cell-to-cell adhesion. This causes flaccid bullae that rupture easily, leaving painful erosions. A key feature is mucosal involvement, especially oral erosions, along with a Nikolsky sign that is positive on both skin and mucosa. The described finding—oral mucosal erosions with fragile bullae and a positive Nikolsky sign—best fits pemphigus vulgaris because it reflects the mucosal involvement, fragile bullae, and the positive Nikolsky sign characteristic of this condition. Other options lack mucosal involvement or describe a Nikolsky sign limited to the skin, which does not align with the typical PV presentation.