What is a key characteristic of bullous pemphigoid?

Bullous pemphigoid is characterized by the presence of tense blisters or bullae that typically arise on normal or slightly erythematous skin, often affecting areas such as the lower abdomen, groin, and medial aspects of the thighs. These bullae are filled with clear fluid and are distinctively tense due to the deep subepithelial cleavage within the dermal-epidermal junction, which is caused by hemidesmosome autoantibodies. The condition is most common in elderly patients and can be associated with pruritus, which often precedes the appearance of blisters.

In the context of the other options, fluid-filled vesicles in children would be more suggestive of conditions such as varicella (chickenpox) or hand-foot-and-mouth disease rather than bullous pemphigoid. Crusted scabs and pustules typically refer to infections like impetigo. Lastly, erosion and ulceration of mucous membranes are associated with other blistering disorders, such as pemphigus vulgaris, which primarily affects mucous membranes and causes pain and erosion rather than the tense bullae characteristic of bullous pemphigoid.