- Bullous pemphigoid diagnosed according to the following criteria: presence of at least 3 of the 4 clinical criteria for bullous pemphigoid as published by the french group for study of blistering diseases (positive predictive value: 95 %: age over 70 years, no lesions on neck or head, absence of atrophic scars, no mucosal lesions.= Histological Examination consistent with BP diagnosis and carried out in the month before inclusion: existence of a sub epidermal blister regardless of its size, containing neutrophils and / or eosinophils associated with a dermal infiltrate consisting of neutrophils and / or eosinophils, or to margination of neutrophils and / or eosinophils along the dermoepidermal junction.= Direct immunofluorescence performed (DIF) in the month preceding inclusion and showing linear deposition of IgG and / or C3 along the dermo-epidermal junction.