Equine congenital papilloma: pathological findings and results of papillomavirus immunohistochemistry in five cases.
Abstract Congenital cutaneous papillomas were identified in five foals. Age at diagnosis ranged from 305 days' gestation to 2 days of age. Breeds were thoroughbred (2), standard-bred (1), warmblood (1) and paint (1). Two were female, one was male and the gender of two cases was not specified. Masses were pedunculated with a roughened, wart-like (verrucous) or a smoother, cauliflower-like surface. Masses occurred as single lesions on the forelimb, lip and face, or as multiple lesions on the trunk. Histological features included relatively uniform epidermal papillary hyperplasia with variable melanin pigment within basal layers and vacuolization of keratinocytes in all layers, but with no evidence of nuclear or cytoplasmic changes (koilocytes) characteristic of viral infection. One case showed epidermal proliferation with proliferation of pilosebaceous units. Results of immunohistochemical studies for the detection of papillomavirus antigens were negative in all cases. These results suggest that equine congenital papilloma may be a hamartomatous lesion (epidermal nevus) and not a viral-induced growth.
College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA.
Kelly S
KS
White
Reina N
RN
Fuji
Beth A
BA
Valentine
Robert J
RJ
Bildfell
D000818:Animals; D000831:Animals, Newborn; D005260:Female; D006734:Horse Diseases / Q000151:congenital / Q000453:epidemiology* / Q000209:etiology / Q000473:pathology; D006736:Horses; D007150:Immunohistochemistry / Q000662:veterinary; D008297:Male; D009518:New York / Q000453:epidemiology; D010212:Papilloma / Q000453:epidemiology / Q000662:veterinary*; D011996:Records / Q000662:veterinary; D012189:Retrospective Studies; D012878:Skin Neoplasms / Q000453:epidemiology / Q000662:veterinary*