Frequency of apoptotic keratinocytes in the feline epidermis: A retrospective light-microscopic study of skin-biopsy specimens from 327 cats with normal skin or inflammatory dermatoses

Abstract

A retrospective light-microscopic study was performed on 294 biopsy specimens of haired skin from cats with various feline inflammatory dermatoses and specimens from cats with normal skin. Conditions expected to frequently have apoptotic epidermal keratinocytes (AKs) (including erythema multiforme, systemic lupus erythematosus, thymoma-associated exfoliative dermatitis, solar dermatitis, and viral dermatopathies) were found to have significantly more AKs than other types of inflammatory dermatoses. Nevertheless, we found more than two AKs in many skin-biopsy specimens from inflammatory conditions not expected to have frequent AKs (especially those from ectoparasitic dermatoses). Only a single AK was found in 1/33 cats with normal skin.

Prevalence of apoptotic epidermal keratinocytes in eosinophilic dermatoses of the cat: A retrospective light-microscopic study of 145 skin-biopsy specimens

“…Of these cases, 18% had eosinophils in close proximity to the AKs. Vogel et al 9 reported this occurrence, but did not determine the prevalence. The significance of this finding is still unclear but might point toward an eosinophil-initiated apoptosis.…”

“…3,4,7,9e13 A recent light-microscopic study looking at the frequency of AKs in various inflammatory dermatoses of the cat reported that e in dermatoses not expected to have high numbers of AKs e ectoparasitic diseases had a higher number of AKs than other inflammatory dermatoses. 9 When examining these cases further, eosinophils were occasionally seen directly adjacent to AKs in flea-bite hypersensitivity, cheyletiellosis, and mosquito-bite hypersensitivity.…”

“…3 To our knowledge, the prevalence of eosinophils in close proximity to AKs in eosinophilic dermatoses of any species has not been previously reported. The role of eosinophils in causing apoptosis of epidermal keratinocytes has been called into question by findings of Vogel et al 9 Because apoptotic cells do not release their cellular components into the surrounding interstitial tissue and are quickly phagocytosed, virtually no inflammatory reaction is incited, making it unlikely that the apoptotic epidermal cells are inducing eosinophil migration. 1,15 Our purposes were to determine: (i) the prevalence of AKs in eosinophilic inflammatory dermatoses of the cat; (ii) the prevalence of eosinophils in close proximity to AKs; and (iii) the association e if any e between the prevalence of AKs and eosinophils in proximity to AKs based on histopathological reaction pattern.…”