What condition is characterized by flaccid bullae affecting the scalp and oral mucosa?

The condition characterized by flaccid bullae affecting both the scalp and oral mucosa is pemphigus vulgaris. This autoimmune disorder is marked by the formation of painful, fragile blisters that can easily rupture, leading to erosions and ulcerations, particularly in mucosal areas like the mouth as well as on the skin.

In pemphigus vulgaris, the presence of antibodies against desmogleins, which are proteins essential for cell adhesion in the epidermis, leads to a loss of cohesion between keratinocytes. This results in the characteristic formation of the blisters. The flaccid nature of the bullae is a distinguishing feature, as they tend to collapse and can develop erosions upon minor trauma.

While other conditions listed may involve blister formation or mucosal symptoms, they have different underlying mechanisms and presentations. For example, Stevens-Johnson syndrome typically presents with more widespread skin involvement and systemic symptoms following medication exposure. Linear IgA disease resembles pemphigus but usually presents with tense bullae and is not specifically associated with oral involvement in the same way. Contact dermatitis can cause vesicular lesions as well but is generally localized and related to exposure to allergens or irritants, without the systemic features or mucosal involvement found in