Pemphigus

The clinical focus is pemphigus vulgaris, the form most associated with painful mucosal disease and fragile skin blisters. It is an autoimmune blistering disorder, not an infection and not a pressure injury. IgG autoantibodies target desmoglein-1 and desmoglein-3. These proteins help neighbouring keratinocytes adhere to one another. When the antibodies disrupt that adhesion, the cells pull apart—a process called acantholysis. The resulting split lies within the epidermis, so the blister roof is thin and easily ruptured. That mechanism explains the bedside picture: - Flaccid bullae break with minor friction and leave moist, painful erosions. - Painful oral erosions may occur before obvious skin lesions and can make chewing, swallowing, and drinking difficult. - Nikolsky sign may be positive: gentle lateral pressure can cause the superficial epidermis to shear. A positive sign supports skin fragility but is not specific enough to establish the diagnosis. Loss of the skin barrier increases fluid loss, pain, and susceptibility to secondary infection. Mucosal involvement adds risks of dehydration, poor nutrition, airway compromise, and ocular injury.