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Conjunctiva: neoplasia

pequis
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Synonym(s): Conjunctival cancer


Introduction

  • A new and abnormal growth on the conjunctiva, specifically one in which cell multiplication is uncontrolled and progressive.
  • Types include: squamous cell carcinoma, mast cell tumor, hemangiosarcoma and lymphoma. Early precancerous changes can be recognized, eg squamous papilloma, carcinoma in situ. Other occasionally identified tumors include basal cell tumor, sarcoma, myxoma, hemangiosarcoma.
  • Both benign and malignant tumors are recognized.
  • Proliferative or erosive/destructive lesions are recognized and some may have both elements present.
  • Cause: various causes for different types of tumor, including ultraviolet light, habronemiasis. 
  • Signs: abnormal conjunctival mass (purulent/cellular), ocular discharge, ocular or periocular irritation with rubbing and even self-trauma, conjunctival inflammation and possibly even reflex uveitis/iridocyclitis, blepharospasm if secondarily infected, photophobia is rare unless intraocular inflammation occurs concurrently.
  • Diagnosis: some types have a characteristic appearance while others are less well-defined and may require biopsy or excisional biopsy.
  • Treatment: surgical removal of tumor mass, cryosurgery or topical antimitotic/cytotoxic compounds. Occasionally radiation brachytherapy can be useful depending on location of lesion. Topical antibiotics frequently required due to high rate of secondary infection, topical steroids can be used to reduced the local inflammation and incidentally have a useful antimitotic effect, but must not be used if there is concurrent corneal erosion or ulceration.
  • Prognosis: variable depending on type of tumor, severity/extent and clinical behavior. Good to poor.

Pathogenesis

Etiology

  • Most types are idiopathic although a carcinogenic change has to occur (spontaneous or induced).
  • Ultraviolet light is appears to be the major carcinogen in squamous cell carcinoma.
  • Conjunctival habronemiasis Habronemiasis may predispose to conjunctival mast cell tumor.
  • No evidence for a viral etiology.

Predisposing factors

General

Timecourse

  • Squamous cell carcinoma Eye: squamous cell carcinoma is slow growing and can be either proliferative and/or ulcerative or complex mixtures of both types.
  • Involvement of cornea (carcinomain situ) involves the corneal epithelium either directly (primary).
  • Hemangiosarcoma Hemangiosarcoma: overviewEye: hemangiosarcoma 01 usually progresses rapidly from a long-standing small red lesion.

Epidemiology

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and 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 Wiley.
  • Knottenbelt D C & Kelly D F (2000) The diagnosis and treatment of periorbital sarcoid in the horse: 445 cases from 1974 to 1999. Vet Ophthal 3 (2), 169-191 PubMed.
  • Paterson S (1997) Treatment of superficial ulcerative squamous cell carcinoma in three horses with topical 5-fluorouracil. Vet Rec 141, 626-628 PubMed.
  • Dugan S J, Curtis C R, Roberts S M et al (1991) Epidemiologic study of ocular/adnexal squamous cell carcinoma in horses. JAVMA 198, 251-255 PubMed.
  • Hacker D V, Moore P F & Buyukmichi N C (1986) Ocular haemangiosarcoma in four horses. JAVMA 189, 200-202 PubMed.
  • Hilbert B J, Farrell R K & Grant B D (1977) Cryotherapy of periocular squamous cell carcinoma in the horse. JAVMA 170, 1305-1308 PubMed.
  • Strafuss A C (1976) Squamous cell carcinoma in horses. JAVMA 168, 61-62 PubMed.
  • Gelatt K N, Myers V S, Perman V et al (1974) Conjunctival squamous cell carcinoma in the horse. JAVMA 168, 617-620 PubMed.

Other sources of information

  • Knottenbelt D C, Patterson-Kane J C & Snalune K L (2015) Clinical Equine Oncology. Elsevier, UK.
  • Brooks D E (2002) Ophthalmology for the Equine Practitioner. Made Easy Series, Teton New Media, USA. pp 45-47.
  • Pascoe R R & Knottenbelt D C (1999) Chapter 19: Neoplastic Conditions. In: Manual of Equine Dermatology. W B Saunders. pp 244-252.
  • Theon A P (1997) Cisplatin Treatment for Cutaneous tumors. In: Current Therapy in Equine Medicine. 4th edn. Ed: Robinson N E. W B Saunders, Philadelphia, USA. pp 372-377.
  • Barnett K C, Crispin S M, Lavach J D & Matthews A G (1995) Upper and Lower Eyelids. In: Colour Atlas and Text of Equine Ophthalmology. Mosby-Wolfe, UK. pp 58-64.
  • Pulley L T & Stannard A A (1990) Tumors of the Skin and Soft Tissues. In: Tumors in Domestic Animals. 3rd edn. Ed: Moulton J E. University of California Press, Berkeley, USA.
  • Lavach J D (1990) Chapter 3: Eyelids. In: Large Animal Ophthalmology. Mosby, USA. pp 4252.

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