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.

Congenital Cutaneous Fibropapillomatosis with No Evidence of Papillomavirus Infection in a Piglet

“…In particular, bovine papilloma virus (BPV) types 1, 2, and 5 induce fibropapilloma of the skin in cattle [4,6]. Congenital papillomas are considered non-infectious lesions that most often occur in horses [5,14,17]. In a previous report on porcine congenital papilloma, the presence of virus was not found on electron microscopy, but there have been no studies using immunohistochemistry or polymerase chain reaction (PCR) to assess for viral involvement [16].…”

Vulvar squamous cell carcinoma in situ within viral papillomas in an aged Quarter Horse mare

“…They can vary from solitary to multiple, and typically undergo spontaneous regression (Jackson 2003). Cutaneous papillomas are occasionally observed in equine fetuses and neonates; however, neither papilloma viral cytopathic effect nor viral antigen expression has been detected within these proliferations, thus they are considered incidental congenital lesions (White et al 2004).…”

Diagnosis of equine penile and preputial masses: A clinical and pathological perspective

“…However, papillomas on the external genitalia of male horses tend to affect older horses and the published mean age range is 16. den Top et al 2008). Both congenital and acquired papillomas have been previously reported (Scott and Miller 2011;White et al 2004). Papillomas begin as small, approximately 1 mm diameter, raised, smooth, shiny grey to white papules (Van den Top et al 2010) and can be present over the whole penis, although most appear over the glans, the urethral process and preputial fold (van den Top et al 2008).…”

“…Both congenital and acquired papillomas have been previously reported (Scott and Miller ; White et al . ). Papillomas begin as small, approximately 1 mm diameter, raised, smooth, shiny grey to white papules (Van den Top et al .…”