Canis ISSN: 2398-2942

Eye: uveal melanoma

Synonym(s): Anterior uveal melanoma, iris melanoma, ciliary body melanoma, choroidal melanoma

Contributor(s): David Gould, Rhea Morgan

Introduction

  • Uveal melanomas usually arise from anterior uveal tract (iris or ciliary body). Primary choroidal melanoma is extremely rare in dogs.
  • Uveal melanocytic tumors may be benign (melanocytoma) or malignant (melanoma), with benign forms predominating in the dog.
  • Most melanomas are darkly pigmented, but amelanotic (pink) melanomas are possible and are usually malignant.

Pathogenesis

Etiology

  • Neoplastic change - predisposing genetic and environmental factors unknown in most dogs.
  • A heritable pattern has been demonstrated in the Labrador and golden retriever (Donaldsonet al, 2006).

Predisposing factors

General
  • Age.
  • Possible breed predisposition in the Labrador retriever, golden retriever, and German shepherd dog.

Pathophysiology

  • Melanocytoma: benign neoplasm with local extension into surrounding tissues, most commonly affecting the iris, ciliary body, and anterior chamber. In time, extrascleral extension and posterior extension along the choroid towards the optic nerve can occur.
  • Malignant melanoma:more aggressive neoplasm, usually with a faster growth rate and more destructive progression. Although uncommon, metastasis is possible at the time of diagnosis.
  • Iris freckle or nevus:benign, focal proliferations of melanocytic cells that are considered benign, nonneoplastic changes. Although the progression of a nevus to a melanocytoma is possible, such progression is poorly documented.

Timecourse

  • Months to years for benign melanomas.
  • Months for malignant melanomas.

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.
  • Alexander A N, Huelsmeyer M K, Mitzev A et al (2006) Development of an allogeneic whole-cell tumor vaccine expressing xenogeneic gp100 and its implementation in a phase II clinical trial in canine patients with malignant melanoma. Cancer Immunol Immunother 55 (4), 433-442 PubMed.
  • Donaldson D, Sansom J, Scase T et al (2006) Canine limbal melanoma: 30 cases (1992-2004). Part 1. Signalment, clinical and histological features and pedigree analysis. Vet Ophthalmol (2), 115-119 PubMed.
  • Milner R J, Salute M, Crawford C et al (2006) The immune response to disialoganglioside GD3 vaccination in normal dogs: a melanoma surface antigen vaccine. Vet Immunol Immunopathol 114 (3-4), 273-84 PubMed.
  • Schub T (2004) New vaccine approach targets melanoma. Lab Anim 33 (8), 9 PubMed.
  • Giuliano E A et al (1999) A matched observational study of canine survival with primary intraocular melanocytic neoplasia. Vet Ophthalmol 2 (3), 185-190 PubMed.
  • Bussanich N M, Dolman P J, Rootman J et al (1987) Canine uveal melanomas: series and literature review. J Am Anim Hosp Assoc 23 (4), 415-422 VetMedResource.
  • Wilcock B P & Peiffer R L (1986) Morphology and Behavior of Primary Ocular Melanomas in 91 Dogs. Vet Pathol 23, 418-424 PubMed.
  • Ryan A M, Diters R W (1984) Clinical and pathologic features of canine ocular melanomas. JAVMA 184, 60-67 PubMed.
  • Diters R W, Dubielzig R R, Aguirre D G, Acland G M (1983) Primary ocular melanomas in dogs. Vet Pathol 20, 379-395 PubMed.
  • Roperto F, Restucci B, Crovace A (1981) Bilateral ciliary body melanomas in a dog. Prog Vet Ophthalmol (4), 149-152 VetMedResource.

Other sources of information

  • Grahn B H & Peiffer R L (2007)Fundamentals of Veterinary Ophthalmic Pathology.In:Veterinary Ophthalmology4th edn. Ed. KN Gelatt, Blackwell Publishing, Iowa, USA, pp3 55-437.
  • Hendrix D V H (2007)diseases and Surgery of the Canine Anterior Segment.In:Veterinary Ophthalmology4th edn. Ed. KN Gelatt, Blackwell Publishing, Iowa, USA, pp812-858.
  • Gould D (2003)Ocular Tumours.In:BSAVA Manual of Canine and Feline Oncology2nd Edition. Eds JM Dobson and BDX Lascelles, BSAVA Publications, UK, pp329-337.
  • Crispin S M (2002)The uveal tract.In:BSAVA Manual of Small Animal Ophthalmology2nd edition. Eds S Petersen-Jones and S Crispin, BSAVA Publications UK, pp162-184.


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