Histopathological development of equine cutaneous papillomas.
Abstract: The histopathological development of equine cutaneous papillomas was studied in 78 warts naturally occurring in 50 one to 3-year-old Thoroughbred or Arab horses and in 54 warts experimentally induced in three 2-year-old Thoroughbreds. Lesions in the natural cases were categorized into three phases, growth, development and regression. Main lesions of the growing phase were marked hyperplasia of the basal cells and mild to moderate acanthosis, hyper- and parakeratosis with a few intranuclear inclusion bodies (IIB) which were positive with anti-bovine papillomavirus serum. In the developing phase, there was prominent acanthosis with cellular swelling and fusion, and marked hyper- and parakeratosis. Many IIB were also present in swollen or degenerative prickle cells and granular cells, with a high degree of parakeratosis in keratinocytes. In the regressing phase, epidermal layers were almost normal with only slight hyperplastic change. However, there was rete peg proliferation downward into the dermis with moderate proliferation of fibroblasts and collagen fibres. In addition, in 10 spontaneous and one experimental wart, the lesions were fibropapillomas and this has never been described in horses previously. It was concluded that papillomas were initiated by basal cell hyperplasia without viral antigen production, with formation of acanthosis and hyper- and parakeratosis with IIB production. These findings were confirmed by examination of the experimental cases on the basis of the gross diameter of the warts.
Publication Date: 1990-05-01 PubMed ID: 2164051DOI: 10.1016/s0021-9975(08)80161-2Google Scholar: Lookup
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- Comparative Study
- Journal Article
Summary
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This research observes the development of horse skin warts, both natural and induced in early-age horses, to understand their progression and the appearance of previously undescribed wart conditions in horses – the fibropapillomas.
Histopathological Examination of Equine Papillomas
- This study focuses on the pathological development of equine cutaneous papillomas, which are basically skin warts that occur in horses.
- An extensive analysis was undertaken on warts naturally occurring in 50 Thoroughbred or Arab horses aged one to three years old, and experimentally induced warts in three 2-year-old Thoroughbreds, resulting in the total study of 132 warts.
Development Phases of Natural Warts
- The researchers found that the lesions on naturally occurring warts could be categorized into three development phases: growth, development, and regression.
- During the growth phase, there were noticeable changes in the base cell layer of the skin, evident through increased cell production (hyperplasia) and slight skin thickening (mild to moderate acanthosis), along with the occurrence of intranuclear inclusion bodies (IIBs) which tested positive for the bovine papillomavirus serum.
- In the development stage, skin thickening became more prominent due to cell swelling and fusion. The degree of keratin produced in the skin layer was high (hyper- and parakeratosis) and there were many instances of IIBs.
- On reaching the regression phase, the skin’s epidermal layer returned to almost normal, barring minor hyperplasia. However, there was noticeable growth of rete pegs (skin protrusions) into the skin’s second layer (the dermis), along with increased production of fibroblasts and collagen fibres.
Fibropapillomas in Horses
- The study also revealed an interesting finding in 10 natural and one experimentally induced warts, which were diagnosed as fibropapillomas, a condition never previously described in horses.
- This finding could contribute significantly to the broader understanding and study of horse health and medical conditions.
Conclusions from the Study
- The researchers concluded that the initial trigger for papillomas in horses is an over-production of base skin cells (basal cell hyperplasia) without viral antigen production.
- This is followed by the formation of acanthosis (skin thickening) and hyper- and parakeratosis (high keratin production) along with the production of intranuclear inclusion bodies (IIBs).
- The study findings were confirmed by examining the induced warts based on their gross diameter.
Cite This Article
APA
Hamada M, Oyamada T, Yoshikawa H, Yoshikawa T, Itakura C.
(1990).
Histopathological development of equine cutaneous papillomas.
J Comp Pathol, 102(4), 393-403.
https://doi.org/10.1016/s0021-9975(08)80161-2 Publication
Researcher Affiliations
- Department of Comparative Pathology, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
MeSH Terms
- Animals
- Epidermis / growth & development
- Female
- Head and Neck Neoplasms / pathology
- Horse Diseases / pathology
- Horses
- Inclusion Bodies
- Keratosis / pathology
- Keratosis / veterinary
- Male
- Papilloma / pathology
- Papilloma / veterinary
- Parakeratosis / pathology
- Parakeratosis / veterinary
- Skin Neoplasms / pathology
- Skin Neoplasms / veterinary
Citations
This article has been cited 2 times.- Diţescu D, Istrate-Ofiţeru AM, Roşu GC, Iovan L, Liliac IM, Zorilă GL, Bălăşoiu M, Cercelaru L. Clinical and pathological aspects of condyloma acuminatum - review of literature and case presentation.. Rom J Morphol Embryol 2021 Apr-Jun;62(2):369-383.
- Postey RC, Appleyard GD, Kidney BA. Evaluation of equine papillomas, aural plaques, and sarcoids for the presence of Equine papillomavirus DNA and Papillomavirus antigen.. Can J Vet Res 2007 Jan;71(1):28-33.
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