Incidence and distribution of subepidermal autoimmune bullous skin diseases in three French regions. Bullous Diseases French Study Group.

Background and Design: The incidence and distribution of autoimmune subepidermal bullous diseases were estimated from prospective data (including immunoelectron microscopy) obtained from 100 cases during a mean period of 35 months in three university dermatologic centers in Amiens, Limoges, and Tours, France, that correspond to a cumulative reference population of 3.55 x 10(6).
Results: Using data from these regions, we found a mean annual incidence of autoimmune subepidermal bullous diseases to be 10.4 per million people and, therefore, estimated the overall number of new cases of these disorders in France to be about 590 cases per year. According to clinical and immunoelectron microscopic criteria, a precise diagnosis was established in 94 cases, distributed as follows: bullous pemphigoid, 69 cases; cicatricial pemphigoid, 12 cases; linear IgA dermatosis, five cases; herpes gestationis, four cases; epidermolysis bullosa acquisita, two cases; and vesiculobullous systemic lupus erythematosus, two cases.
Conclusion: Our prospective study is the first assessing the incidence and distribution of autoimmune subepidermal bullous disorders that systematically included immunoelectron microscopic data. Our estimated incidence of bullous pemphigoid (seven new cases per million people per year) is large enough to establish bullous pemphigoid as the major autoimmune subepidermal bullous disease for the purpose of therapeutic trials. On the contrary, all other disorders, particularly epidermolysis bullosa acquisita (estimated annual incidence, 0.17 to 0.26 per million people), were very rare and reflect the paucity of patients available for short-term clinical studies in France.