This condition is characterized by classic target lesions, some of which may have central blisters, a morphology distinct from the flaccid bullae of impetigo.
This is distinguished by a history of bites and presents as tense bullae arising on top of inflamed, edematous papules, often in a grouped or linear pattern.
Stroking a lesion of mastocytosis causes it to become a wheal (Darier's sign), a reaction not seen in the other conditions, and the blisters arise from urticarial plaques.
Herpes presents as grouped vesicles on an erythematous base, which are smaller and more uniform than the larger, flaccid, and fragile bullae of bullous impetigo.
Bullous pemphigoid is characterized by large, tense bullae on either erythematous or normal-appearing skin, typically in an older individual, and is confirmed by immunofluorescence, unlike the superficial, easily ruptured bullae of impetigo.
