Two patients had vesiculobullous dermatoses that combined features of dermatitis herpetiformis (DH) and either pemphigus vulgaris or pemphigus foliaceus. Both patients responded to treatment with sulfones. The literature contains similar reports, as well as reports of cases of vesiculobullous dermatoses that combine features of DH and bullous pemphigoid (BP).
There is evidence that a similar immune mechanism exists for DH, pemphigus, and BP. The presence of indeterminate or hybrid cases and their similar immunopathological features suggest that these three diseases may be related clinically and immunologically. Such hybrid or indeterminate cases may be referred to as "mixed bullous disease."
Barranco VP. Mixed Bullous Disease. Arch Dermatol. 1974;110(2):221-224. doi:10.1001/archderm.1974.01630080023006