Equis ISSN 2398-2977

Skin: neoplasia - squamous cell carcinoma

Contributor(s): Cody Coyne, Prof Derek Knottenbelt, Dawn Logas, Sue Paterson, Anna Hollis

Introduction

  • Proliferative epithelial form of neoplasia affecting non-pigmented dermal structures of the urogenital tract and eyelids, may also be seen in other locations and on pigmented skin.
  • Cause: UV radiation, unpigmented sparsely haired skin and the carcinogenic properties of equine smegma have all been implicated. The appearance of lesions on both pigmented and unpigmented skin makes the cause even more uncertain.
  • Signs: usually solitary masses at mucocutaneous junctions, on eyelids and external genitalia. May be proliferative or destructive in nature.
  • Diagnosis: appearance of mass, confirmation by biopsy and histopathology.
  • Treatment: radical surgical excision, radioactive implants, 5-fluorouracil.
  • Prognosis: variable; all malignant, locally aggressive, some metastasize - poor if rapidly growing.
Print off the Owner factsheets on Cancer in horses and Lumps and bumps to give to your clients.

Pathogenesis

Etiology

  • Postulated associated causes:
    • Chronic exposure to UV light.
    • Carcinogenic properties of equine smegma (geldings (penile and preputial forms) and mares (clitoral)).
    • Unpigmented, sparsely haired skin.
    • Relationship to viruses uncertain.

Predisposing factors

General

  • Unpigmented, sparsely haired skin.

Pathophysiology

  • All malignant, locally invasive.
  • Slow-growing or rapidly invasive tumors in areas of non-pigmented skin primarily.
  • Ulcerative lesion of granulation-like tissue on third eyelid, conjunctiva, limbus, cornea, eyelids , and genitalia, lips and facial skin, perineal skin.
  • Metastatic potential.

Timecourse

  • Varies.
  • Some highly active, very rapidly growing, others are slow growing.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Barrelet A, Foote A & Littlewood J D (2010) Common equine skin tumours. UK Vet 15 (6), 9-17 VetMedResource.
  • Serena A, Naranjo C, Kock C & Darien B J (2009) Resection cystoplasty of a squamous cell carcinoma in a mare. Equine Vet Educ 21 (5), 263-266 VetMedResource.
  • Elce Y A (2009) The aetiopathogenesis of squamous cell carcinomas in horses. Equine Vet Educ 21 (1), 17-18 VetMedResource.
  • Henson F M D & Dobson J M (2004) Use of radiation therapy in the treatment of equine neoplasia. Equine Vet Educ 16 (6), 315-318 VetMedResource.
  • Quinn C (2003) Skin tumours in the horse: clinical presentation and management. In Pract 25 (8), 476-483 VetMedResource.
  • Pascoe R R (1991) Equine nodular and erosive skin conditions - the common and not so common. Equine Vet Educ (3), 153-159 VetMedResource.
  • Bertone A L & McClure J J (1990) Therapy for sarcoids. Comp Contin Educ Prac Vet 12 (2), 262-265 VetMedResource.


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