Review Question - QID 101305

IgG antibodies against hemidesmosomes characterize bullous pemphigoid, an autoimmune skin disorder. Hemidesmosomes are present linearly along the epidermal basement membrane and help to anchor the basal epidermis to the extracellular matrix.

Afflicted patients present with a rash of vesicles and tense blisters. Though similar to pemphigus vulgaris, bullous pemphigoid is less severe, spares the oral mucosa, and has a negative Nikolsky’s sign (the epidermis does not separate upon light stroking of the skin). Pemphigus vulgaris has flaccid rather than tense blisters.

Bickle et al. review bullous dermatoses. Bullous pemphigoid is rarely fatal, even if untreated. It presents as tense bullae with clear fluid or erosions. It is most often located on the lower legs, forearms, thighs, groin, and abdomen, but rarely found on mucosa.

Tsuruta et al. review the role of hemidesmosomes in bullous diseases. Several autoimmune disorders target hemidesmosome components. In bullous pemphigoid, autoantibodies create a linear deposit of IgG at the epidermal basement membrane.

Illustration A shows bullous pemphigoid; note the tense bullae with clear fluid. Illustration B shows immunoflourescent IgG deposited linearly along the epidermal basement membrane in bullous pemphigoid.

Incorrect answers:
Answer 2: IgG antibodies against desmosomes cause pemphigus vulgaris and are seen upon immunofluorescence in net-like patterns around epidermal cells above the epidermal basement membrane.
Answer 3: Dermatitis herpetiformis is marked by IgA deposits at the tips of dermal papillae (small extensions of the dermis into the epidermis).
Answer 4: Erythema nodosum is the inflammatory hypersensitivity reaction against subcutaneous fat that may produce tender, red nodules or lumps.
Answer 5: Direct immunofluorescence often demonstrates IgG antinuclear antibodies within the nuclei of epidermal cells in both cutaneous lupus and systemic lupus erythrematosus.