Lichen planus pemphigoides, a possible example of epitope spreading.

Oral lichen planus and mucous membrane pemphigoid are 2 autoimmune chronic inflammatory diseases with different clinical features. Their pathogenesis is also different, with oral lichen planus characterized by a cellular autoimmune response (lymphocytic-mediated) and mucous membrane pemphigoid determined by immunoglobulin-mediated humoral autoimmune activity. We report the cases of 2 female patients who, after an initial diagnosis of oral lichen planus, developed mucous membrane pemphigoid in a period ranging from 3 to 11 years. Both of these disorders were diagnosed via clinical, histologic, and immunologic parameters. They were refractory to conventional immunosuppressive therapy but responsive to intravenous immunoglobulin therapy. Further investigations are necessary to better elucidate whether and how a progressive development from one unrelated immunologic disorder to another may occur. Data provided herein allows us to hypothesize that epitope spreading phenomenon might be the underlying mechanism.