A

Pemphigus produces flaccid, intra-epithelial (intra-epidermal) bullae because auto-antibodies disrupt desmosomal adhesion between keratinocytes; in contrast, bullous pemphigoid, lichen planus with bullae, and other forms of pemphigoid create sub-epidermal blisters beneath the basement membrane [Song et al., 2014, PMID 25780973].