Patho-histological features of fibroblastic sarcoid in horses

  • M. Portenko National University of Veterinary Medicine and Biotechnologies named after Stepan Gzhytskyi
  • O. Shchebentovska National University of Veterinary Medicine and Biotechnologies named after Stepan Gzhytskyi
Keywords: skin; papillomavirus; hyperkeratosis; necrobiosis; collagen fibers; moiré structures; fibroblasts.


Sarcoid is one of the most common skin tumours, which is diagnosed in various breeds of horses at any age regardless of the animal’s sex. Such fibroblastic neoplasm manifests itself in several clinical ways with its specific morphological features. As a rule, it metastasizes rarely but can be locally invasive. The disease’setiology is multifactorial and includes the confirmed role of the bovine papillomavirus and genetic and environmental factors. The article introduces the results of a retrospective study of horses of the Ukrainian riding breed with a fibroblastic sarcoid type, which was localized mainly in the area of the external thoracic vein. Neoplasms were represented by two types. The first one included broad base neoplasms without a pronounced pedicle but with signs of hyperkeratosis. Massive rounded dense formations with an ulcerated surface refer to the second type. To verify the studied types of sarcoid, wide surgical excision of the lesion’svisible parts was performed, followed by the selection of fragments for the pathohistological diagnosis. Also, additional staining methods were used to detect the connective and muscle tissue (Van Gieson’s staining) and elastic fibers (Weigert’s resorcin-fuchsin staining). Microscopically, the neoplasm without a visible pedicle showed signs of hyperkeratosis and acanthosis in the peritumoral epidermal layer. Epidermis desquamation with a significant amount of oxyphilic detritus, diapedesis hemorrhages, and dilated vessels was also detected in some areas. Chaotic placement of fibroblasts and fibrocytes was noted, to a greater extent, subdermally. Anisocytosis and anisokaryosis were expressed moderately. Sarcoids, macroscopically presented in the form of massive dense formations with an ulcerated surface, were histologically characterized by the replacement of the epidermis with cellular elements, subdermal hemorrhages, and the characteristic perpendicular orientation of coarse collagen fibers towards the basement membrane. Closely spaced spindle-shaped cells with fibers forming moiré structures were visualized in the deep dermis layers. Nuclei were hyperchromic and elongated in shape, no atypical mitoses were noted. Pathohistological examination during the identification of a sarcoid type for diagnostic purposes can cause rapid growth and formation of an ulcer. The final diagnosis regarding equine sarcoid can be made based on a combination of clinical signs, histopathological examination, and molecular genetic testing with the isolation of BPV DNA.


Angelos, J. A., Marti, E., Lazary, S., & Carmichael, L. E. (1991). Characterization of BPV-like DNA in equine sarcoids. Archives of Virology, 119, 95–109.

Bergvall, K. E. (2013). Sarcoids. The Veterinary clinics of North America, Equine Practice, 29(3), 657–671.

Berruex, F., Gerber, V., Wohlfender, F. D., Burger, D., & Koch, C. (2016). Clinical course of sarcoids in 61 Franches-Montagnes horses over a 5–7 year period. The Veterinary Quarterly, 36(4), 189–196.

Bogaert, L., Martens, A., De Baere, C., & Gasthuys, F. (2005). Detection of bovine papillomavirus DNA on the normal skin and in the habitual surroundings of horses with and without equine sarcoids. Research in Veterinary Science, 79(3), 253–258.

Bogaert, L., Van Heerden, H., De Cock, H. E. V., Martens, A., & Chiers, K. (2011). Molecular and immunohistochemical distinction of equine sarcoid from schwannoma. Veterinary Pathology, 48(3), 737–741.

Bogaert, L., Van Poucke, M., De Baere, C., Dewulf, J., Peelman, L., Ducatelle, R., Gasthuys, F., & Martens, A. (2007). Bovine papillomavirus load and mRNA expression, cell proliferation and p53 expression in four clinical types of equine sarcoid. The Journal of General Virology, 88(8), 2155–2161.

Chambers, G., Ellsmore, V. A., O’Brien, P. M., Reid, S. W. J., Love, S., Campo, M. S., & Nasir, L. (2003). Association of bovine papillomavirus with the equine sarcoid. The Journal of General Virology, 84(5), 1055–1062.

Cotchin, E. (1977). A general survey of tumours in the horse. Equine Veterinary Journal, 9, 16–21.

Epperson, E. D., & Castleman, W. L. (2017). Bovine papillomavirus DNA and S100 profiles in sarcoids and other cutaneous spindle cell tumors in horses. Veterinary Pathology, 54(1), 44–52.

Finlay, M., Yuan, Z., Burden, F., Trawford, A., Morgan, I. M., Campo, M. S., & Nasir, L. (2009). The detection of bovine papillomavirus type 1 DNA in flies. Virus Research, 144(1–2), 315–317.

Foy, J. M., Rashmir-Raven, A. M., & Brashier, M. K. (2002). Common equine skin tumors. Compendium on Continuing Education for the Practicing Veterinarian, 24, 242–255.

Gebre, D., Gizachewu, A., & Negero, J. (2018). Equine sarcoid: Epidemiology and its clinical impact in working donkeys in selected districts of Central Ethiopia. Journal of Veterinary Science and Technology, 9(3), 537.

Giraldo, A., Pinard, C. L., Plattner, B. L., & Dubois, M. S. (2020). Periocular sarcoid with bone invasion in a Thoroughbred mare. The Canadian Veterinary Journal, 61(4), 415–419.

Goodrich, L., Gerber, H., Marti, E., & Antczak, D. F. (1998). Equine sarcoids. Veterinary Clinics of North America, Equine Practice, 14(3), 607–623.

Gysens, L., Vanmechelen, B., Haspeslagh, M., Maes, P., & Martens, A. (2022). New approach for genomic characterisation of equine sarcoid-derived BPV-1/-2 using nanopore-based sequencing. Virology Journal, 19(1), 8.

Hallamaa, E., Saario, E., & Tallberg, T. (2005). Macroscopical and histopathological changes in regressing primary and recurrent equine sarcoids during active specific bio-immunotherapy. In Vivo, 19(4), 761–767.

Hartl, B., Hainisch, E. K., Shafti-Keramat, S., Kirnbauer, R., Corteggio, A., Borzacchiello, G., Tober, R., Kainzbauer, C., Pratscher, B., & Brandt, S. (2011). Inoculation of young horses with bovine papillomavirus type 1 virions leads to early infection of PBMCs prior to pseudo-sarcoid formation. The Journal of General Virology, 92(10), 2437–2445.

Haspeslagh, M., Gerber, V., Knottenbelt, D. C., Schüpbach, G., Martens, A., & Koch, C. (2018). The clinical diagnosis of equine sarcoids-Part 2: Assessment of case features typical of equine sarcoids and validation of a diagnostic protocol to guide equine clinicians in the diagnosis of equine sarcoids. Veterinary Journal, 240, 14–18.

Kasperowicz, B., Rotkiewicz, T., & Domagala, O. I. (2006). Pathomorphological and immunohistochemical study of selected markers of tumour cell proliferation in equine sarcoid. Polish Veterinary Journal, 9(2), 109–119.

Knottenbelt, D. C. (2005). A suggested clinical classification for the equine sarcoid. Clinical Techniques in Equine Practice, 4(4), 278–295.

Knottenbelt, D. C. (2019). The equine sarcoid: Why are there so many treatment options? The Veterinary Clinics of North America, Equine Practice, 35(2), 243–262.

Knottenbelt, D. C., & Matthews, J. B. (2001). A positive step forwards in the diagnosis of equine sarcoid. Veterinary Journal, 161(3), 224–226.

Knottenbelt, D. C., Schumacher, J., & Toth, F. (2016). Sarcoid transformation at wound sites. In: Equine wound management. Third edition. Wiley-Blackwell. Pp. 490–507.

Knowles, E. J., Tremaine, W. H., Pearson, G. R., & Mair, T. S. (2016). A database survey of equine tumours in the United Kingdom. Equine Veterinary Journal, 48(3), 280–284.

Koch, C., Martens, A., Hainisch, E. K., Schüpbach, G., Gerber, V., & Haspeslagh, M. (2018). The clinical diagnosis of equine sarcoids – Part 1: Assessment of sensitivity and specificity using a multicentre case-based online examination. Veterinary Journal, 242, 77–82.

Lane, J. G. (1977). The treatment of equine sarcoids by cryosurgery. Equine Veterinary Journal, 9, 127–133.

Martens, A., De Moor, A., Demeulemeester, J., & Ducatelle, R. (2000). Histopathological characteristics of five clinical types of equine sarcoid. Research in Veterinary Science, 69(3), 295–300.

Marti, E. L. S., Antczak, D. F., & Gerber, H. (1993). Report of the first international workshop on equine sarcoid. Equine Veterinary Journal, 25, 397–407.

Marti, E., Lazary, S., Antczak, D. F., & Gerber, H. (1993). Report of the first international workshop on equine sarcoid. Equine Veterinary Journal, 25(5), 397–407.

Merkulov, G. A. (1969). Kurs patologicheckoj tekhniki [Course of pathohistological techniques]. Medicine, Moscow (in Russian).

Miller, R. I., & Campbell, R. S. F. (1982). A survey of granulomatous and neoplastic diseases of equine skin in North Queensland. Australian Veterinary Journal, 59, 33–37.

Nasir, L., & Campo, M. S. (2008). Bovine papillomaviruses: Their role in the aetiology of cutaneous tumours of bovids and equids. Veterinary Dermatology, 19(5), 243–254.

Ogłuszka, M., Starzyński, R. R., Pierzchała, M., Otrocka-Domagała, I., & Raś, A. (2021). Equine sarcoids – causes, molecular changes, and clinicopathologic features: A review. Veterinary Pathology, 58(3), 472–482.

Otten, N., von Tscharner, C., Lazary, S., Antczak, D., & Gerber, H. (1993). DNA of bovine papillomavirus type 1 and 2 in equine sarcoids: PCR detection and direct sequencing. Archives of Virology, 132, 121–131.

Ragland, W. L., Keown, G. H., & Spencer, G. R. (1970). Equine sarcoid. Equine Veterinary Journal, 2, 2–11.

Rodrigues, M. A. C., Simões, B. V., Lemos, V. Z., Pereira, M. M., Costa, B. O., Rondon, D. A., & Pereira, C. M. (2022). Equine sarcoid. EAS Journal of Veterinary Medical Science, 4(2), 16–18.

Scagliarini, A., Bettini, G., Savini, F., Spadari, A., Sonvico, F., Balducci, A. G., Calbucci, S., & Colombo, G. (2012). Treatment of equine sarcoids. Veterinary Record, 171, 330–330.

Scott, D. W., & Miller, W. H. (2003). Neoplastic and non-neoplastic tumors. In: Equine Dermatology. St. Louis, Missouri, Saunders. Pp. 719–731.

Taylor, S., & Haldorson, G. (2013). A review of equine sarcoid. Equine Veterinary Education, 25(4), 210–216.

Trewby, H., Ayele, G., Borzacchiello, G., Brandt, S., Campo, M. S., Del Fava, C., Marais, J., Leonardi, L., Vanselow, B., Biek, R., & Nasir, L. (2014). Analysis of the long control region of bovine papillomavirus type 1 associated with sarcoids in equine hosts indicates multiple cross-species transmission events and phylogeographical structure. The Journal of General Virology, 95(12), 2748–2756.

Wilson, A. D., Armstrong, E. L. R., Gofton, R. G., Mason, J., De Toit, N., & Day, M. J. (2013). Characterisation of early and late bovine papillomavirus protein expression in equine sarcoids. Veterinary Microbiology, 162(2–4), 369–380.

Wobeser, B. K. (2017). Making the diagnosis: Equine sarcoid. Veterinary Pathology, 54(1), 9–10.

Wobeser, B. K., Davies, J. L., Hill, J. E., Jackson, M. L., Kidney, B. A., Mayer, M. N., Townsend, H. G., & Allen, A. L. (2010). Epidemiology of equine sarcoids in horses in Western Canada. The Canadian Veterinary Journal, 51(10), 1103–1108.

Yuan, Z., Gault, E. A., Campo, M. S., & Nasir, L. (2011). Different contribution of bovine papillomavirus type 1 oncoproteins to the transformation of equine fibroblasts. The Journal of General Virology, 92(4), 773–783.

How to Cite
Portenko, M., & Shchebentovska, O. (2022). Patho-histological features of fibroblastic sarcoid in horses . Regulatory Mechanisms in Biosystems, 13(4), 393-399.