Fig. 6

Histological characteristics of canine pemphigus vulgaris. a and b: a suprabasal cleft in the epidermis is due to keratinocyte acantholysis. Characteristically, a single row of individualized and rounded basal keratinocytes remains attached to the dermis below the cleft, seen best in image b (inset from a; arrows). Inflammation in the vesicle lumen is absent and it is minimal in the epidermis and dermis; c: the base of a suprabasal cleft in some patients is lined by basal keratinocytes that do not separate significantly on their sides. In the vesicle lumen, neutrophils and fewer mononuclear cells are present with a few individual and small “rafts” or clusters of acantholytic keratinocytes (arrows). Lymphocytic exocytosis in the epidermis is mild to moderate, as is dermal neutrophilic and lymphoplasmacytic inflammation. Eosinophils can occur (not shown); d: suprabasal clefts extend along the hair follicle infundibulum, as well as the sebaceous gland duct, and inflammation is minimal. a, c and d 20x - magnification. b – 63x magnification. Hematoxylin and eosin. All pictures are courtesy of Keith E. Linder