À suspecter devant toute éruption bulleuse ou prurit tenace (parfois isolé).

Bullous pemphigoid, a dermatosis of the elderly. Bullous pemphigoid is the most common autoimmune bullous disease and affects almost exclusively the elderly. Its occurrence is related to the presence of pathogenic autoantibodies directed against structural proteins (BP180 and BP230) of the protein adhesion complex of the dermo-epidermal junction: the hemi-desmosome. Bullous pemphigoid is classically characterized by pruritus and the appearance of blisters on an inflammatory background with a symmetrical topography: thighs, arms and trunk. Blisters eventually break, leading to erosions. Mucosal involvement is rare. Histology of a cutaneous biopsy finds a subepidermal blister containing eosinophils. Direct immunofluorescence confirms the diagnosis by the presence of linear deposits of IgG and C3 along the epidermal basement membrane. The reference treatment is the superpotent topical corticosteroid therapy (clobetasol propionate).