Which of the following is a characteristic feature of pemphigus vulgaris?

Pemphigus vulgaris is a rare autoimmune blistering disorder that primarily affects the skin and mucous membranes. One of its hallmark features is the formation of large, flaccid bullae. These bullae tend to be fragile and burst easily, leading to painful erosions. The pathophysiology involves the presence of autoantibodies directed against desmogleins, which are proteins essential for cell adhesion in the epidermis. As a result, the skin becomes less stable, and blisters form more readily.

The large size and ease of rupture of these blisters characterize pemphigus vulgaris, making option B correct. The other features listed in the question do not accurately describe pemphigus vulgaris. Subdermal bullae are typical of other blistering disorders, while cysts filled with clear fluid are not associated with this condition, and erythematous plaques do not represent the typical presentation of pemphigus vulgaris. Understanding these features helps in clinical recognition and diagnosis of the disease.