Acute allergic contact dermatitis presents with weeping vesicles and intense itch in a pattern corresponding to an allergen, unlike the large, tense, autonomous bullae of BP.
EBA is clinically very similar but is distinguished by its tendency to affect trauma-prone sites (hands, feet), heal with scarring and milia, and a different immunofluorescence pattern.
An exaggerated insect bite reaction can cause bullae, but these arise from intensely itchy, inflamed papules and follow a distribution of bites on exposed skin.
This condition is characterized by an "annular jewel-like" arrangement of vesicles and bullae, and is defined by the specific finding of linear IgA deposition on immunofluorescence.
While a blistering disease, MMP has a clear predilection for mucosal surfaces (oral, ocular) and leads to significant scarring, which is not a primary feature of BP.
This is a pruritic eruption of pregnancy, distinguished by its onset during gestation, periumbilical involvement, and resolution after delivery.
Pemphigus vulgaris is characterized by more superficial, flaccid bullae that rupture easily to leave painful erosions, and it typically starts in the mouth, unlike the tense, intact bullae of BP.
This is a pruritic rash of pregnancy, but it is primarily composed of urticarial papules and plaques within striae, with blistering being a rare and minor component.
While BP can start with urticarial plaques, it is distinguished by the subsequent development of large, tense bullae, which do not occur in simple urticaria.
