Canine hyperplastic intraepidermal pustular and suprabasal acantholytic dermatosis with features of human pemphigus vegetans.

Pemphigus vegetans is a rare autoimmune blistering acantholytic dermatosis of humans that combines unusually hyperplastic and verrucous pustular skin lesions and mucosal erosions. We report herein the clinical, histopathologic, and immunologic findings in a dog whose lesions resembled, but were not identical to, those of human pemphigus vegetans. A 4-year-old male Greater Swiss Mountain Dog presented with multifocal cutaneous verrucous and crusted papules and pustules, as well as skin and mucosal erosions and ulcers. Microscopic lesions consisted of exophytic papillated epidermal hyperplasia, superficial and deep intraepidermal acantholytic neutrophilic and eosinophilic pustules, and suprabasal epidermal clefts leaving rounded basal keratinocytes at the bottom of the vesicles. Direct and indirect immunofluorescence revealed antikeratinocyte IgG autoantibodies. Immunoprecipitation immunoblotting and immunoabsorption experiments with recombinant canine desmogleins confirmed that autoantibodies recognized desmoglein-1. In this dog, clinical and histopathologic features resembled those of human pemphigus vegetans, while circulating autoantibodies against canine desmoglein-1 were solely identified. This antigen target is different from that of the human disease in which antidesmoglein-3 autoantibodies are detected most commonly.