Pilosebaceous Dysplasia (Abnormal Orientation of Pilosebaceous Units): A Histopathological Finding Indicative of Yeast Dermatitis in Dogs

Abstract

The objective of this study was to characterize the histological appearance, prevalence, and association of pilosebaceous dysplasia (PD) in dogs with yeast dermatitis. A retrospective, light-microscopic study of H&E-stained skin-biopsy specimens from 670 dogs with non-neoplastic dermatoses and 28 normal dogs was performed. Chi-square and rank-sum analyses were used to compare the prevalence and abundance of PD in dogs with yeast dermatitis, normal dogs, and dogs with non-yeast dermatoses. PD was observed in 76 of 98 (78%; 95%confidence interval (CI) 68%, 85%) of dogs with yeast dermatitis and in 14 of 572 (2.4%; CI 1.4%, 4.2%) dogs with non-yeast dermatoses. PD was not observed in any normal dogs (CI 0%, 15%). The prevalence (presence, yes/no) of PD was significantly greater in dogs with yeast dermatitis (chi-square = 424.49; degrees of freedom = 2; p<0.0001) than in dogs with non-yeast dermatoses and in normal dogs. Also, among the dogs with PD present, the percentage of affected units in each dog was greater (p=0.0002) in dogs with yeast dermatitis (minimum 12%; median75%; maximum 100% affected units/dog) than in dogs with nonyeast dermatoses (minimum 3%; median 30%; maximum 100%). There was no significant difference (p>0.05) between the prevalence of PD in dogs with non-yeast dermatoses and in normal dogs. These findings suggest that the finding of PD in skin-biopsy specimens of dogs is significantly associated with yeast dermatitis and could be considered when making this histological diagnosis.