Equis ISSN 2398-2977

Skin: neoplasia - squamous cell carcinoma

Contributor(s): Cody Coyne, Prof Derek Knottenbelt, Dawn Logas, Sue Paterson, Vetstream Ltd

Introduction

  • Most common genuine skin neoplasm.
  • Proliferative epithelial form of neoplasia affecting non-pigmented dermal structures of the urogenital tract and eyelids.
  • Cause: UV radiation, unpigmented sparsely haired skin and the carcinogenic properties of equine smegma have all been implicated.
  • Signs: usually solitary masses at mucocutaneous junctions, on eyelids and external genitalia.
  • 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 to metastasize.
  • 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.
  • Slow to metastasize.

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 Vet15(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 Educ21(5), 263-266 VetMedResource.
  • Elce Y A (2009)The aetiopathogenesis of squamous cell carcinomas in horses.Equine Vet Educ21(1), 17-18 VetMedResource.
  • Henson F M D & Dobson J M (2004)Use of radiation therapy in the treatment of equine neoplasia.Equine Vet Educ16(6), 315-318 VetMedResource.
  • Quinn C (2003)Skin tumours in the horse: clinical presentation and management.In Pract25(8), 476-483 VetMedResource.
  • Pascoe R R (1991)Equine nodular and erosive skin conditions - the common and not so common.Equine Vet Educ3(3), 153-159 VetMedResource.
  • Bertone A L & McClure J J (1990)Therapy for sarcoids.Comp Contin Educ Prac Vet12(2), 262-265 VetMedResource.


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