Acquired bullous disease

Key Features: Pemphigus is a group of autoimmune blistering diseases that affect the skin and mucous membranes and has three major forms: pemphigus vulgaris, pemphigus foliaceus, and paraneoplastic pemphigus. It is characterized histologically by intraepi-thelial blister formation caused by the loss of cell-to-cell adhesion of keratinocytes (acan-tholysis) and immunopathologically by the presence of tissue-bound and circulating IgG autoantibodies directed against the cell surface of keratinocytes or desmogleins. Desmogleins (Dsg1 and Dsg3) are the target antigens in pemphigus, and the clinical pheno-type is correlated with the patient's antides-moglein autoantibody profile. Paraneoplastic pemphigus occurs in association with underlying neoplasms and shows severe oral and conjunctival erosions with polymorphous skin eruptions. Paraneoplastic pemphigus is caused by humoral (IgG autoan-tibodies against Dsg3, Dsg1, and plakin molecules), as well as cellular, autoimmunity. Bulbous pemphigoid is a subepidermal autoimmune blistering disease that most commonly occurs in the elderly. The clinical presentation is typically a pruritic eruption with widespread tense blisters. It is immunopathologically characterized by in vivo bound IgG and C3 at the dermoepidermal junction. The target antigens in bullous pemphigoid are BP230(BPAG1 or BP230) and BP180(BPAG2 or type XVII collagen), which are found in hemidesmosomes along the basement membrane zone. Epidermolysis bullous acquisita is a rare and acquired bullous disease associated with IgG autoantibodies against type VII collagen, which is the major component of anchoring fibrils. Systemic corticosteroids are the mainstay of therapy for acquired autoimmune bullous disease, and adjuvant therapies, including immunosup-pressive agents, plasmapheresis, high-dose intravenous immunogloblin, and biological agents, are used for severe cases.