The main autoimmune bullous dermatoses are pemphigus and cicatricial pemphigoid. Pemphigus is an autoimmune dermatological disease characterized by the production of anti-desmoclesin antibodies 1 and 3, affecting the skin and mucous membranes.The cicatricial pemphigoid is an autoimmune dermatological disease, characterized by the production of anti-zone antibodies of the basal membrane and characterized by a predominant mucosal involvement. Mycophenolic acid (MPA) is an increasingly used form of corticosteroid. Despite its increasing use, pharmacokinetics in autoimmune bullous dermatosis remain little studied.

Inclusion Criteria:

• Age > or = 18 years.
• Patient treated by Mycophénolate Mofétil (MMF) per os (Cellcept®) for an autoimmune bullous dermatose (pemphigus or cicatricial pemphigoid) for at least 30 days according to the recommendations (PNDS Pemphigus and cicatricial pemphigoid HAS 2011)
• Patient able to understand the nature, purpose and methodology of the study
• Patient affiliated to the French social security system or equivalent
• Patient who have signed an informed consent form

Exclusion Criteria:

• Pregnant or breast-feeding women or women of childbearing potential without efficient contraception (based on a declaration)
• Patient under legal protection.
• Patient deprived of freedom
• Patient with any altered mental status or any psychiatric condition that would interfere with the understanding of the study.