felis - Articles
Melanoma
Introduction
- Less common in the cat than in the dog and horse, but not rare, comprising <2% of feline tumors, and 0.5% of feline skin tumors.
- Eye and skin affected more often than oral cavity.
- Diagnosis: cytology, histopathology.
- Treatment: surgical resection +/- radiotherapy & chemotherapy +/- immunotherapy.
- Prognosis: 29-47% of melanocytic feline skin tumors are benign. Recurrence and metastasis are common in malignant melanoma. Print off the owner factsheet on cancer Cancer in your cat - possible options to give to your client.
Presenting signs
Cutaneous
- Solitary, dome-shaped, pigmented mass.
- Occasionally, pedunculated, friable, ulcerated, hemorrhagic.
- Can be non-pigmented.
Ocular
- Blindness, glaucoma, uveitis.
- Irregular pupil, enlarged globe, opacified cornea
. - Scleral/conjunctival congestion.
- Visible ocular/intra-ocular mass Eye: intraocular mass.
- Begins as asymmetrical pigmentation of iris Eye: uveal melanoma.
Geographic incidence
- Uncommon to rare.
Age predisposition
- Old cats (10-12 years).
- Age range for melanocytic neoplasia of the skin in cats is 3-19 years (mean = 11.5 years).
Breed/Species predisposition
- Some reports suggest domestic shorthaired cats at increased risk, but not confirmed.
Pathogenesis
Etiology
- Occur experimentally with feline sarcoma virus (FeSV) Feline sarcoma virus infection.
- Unlikely to be cause of naturally occurring melanomas.
Pathophysiology
- Neuroecrodermal origin.
- Melanin is transferred to keratinocytes.
- Benign tumors - local problem only.
- Malignant tumors - metastasis to distant sites (lung and liver common), usually via lymph nodes.
Cutaneous
- Primary mass may not cause a problem unless very large.
Ocular
- Primary mass may obscure vision or cause secondary glaucoma, uveitis.
- Eyelid and ocular surface - majority malignant.
- Limbic (scleral/subconjunctival) - majority benign.
- Intra-ocular - majority malignant but slow time course for both primary lesion and metastasis.
- Feline conjunctival lymphoma - majority malignant.
Timecourse
- Benign tumors slow growing.
- Malignant tumors often slow to metastasize - several years for ocular lesions.
- Malignant cutaneous melanomas very aggressive and metastasize rapidly (rare).
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.
- Sarbu L, Kitchell B E, Bergman P J (2017) Safety of administering the canine melanoma DNA vaccine (Oncept) to cats with malignant melanoma - a retrospective study. J Feline Med Surg 19 (2), 224-230 PubMed.
- Wiggans K T, Reilly C M, Kass P H et al (2016) Histologic and immunohistochemical predictors of clinical behavior for feline diffuse iris melanoma. Vet Ophthalmol 19 (Suppl 1), 44-55 PubMed.
- Schobert C S, Labelle P, Dubielzig R R (2010) Feline conjunctival melanoma: histopathological characteristics and clinical outcomes. Vet Ophthalmol 13 (1), 43-46 PubMed.
- Farrelly J, Denman D L, Hohenhaus A E et al (2004) Hypofractionated radiation therapy of oral melanoma in five cats. Vet Radiol Ultrasound 45 (1), 91-93 PubMed.
- Ramos-Vara J A, Miller M A, Johnson G C et al (2002) Melan A and S100 protein immunohistochemistry in feline melanomas: 48 cases. Vet Pathol 39 (1), 127-132 PubMed.
- Smith S H, Goldschmidt M H, & McManus P M (2002) A comparative review of melanocytic neoplasms. Vet Pathol 39 (6), 651-678 PubMed.
- Luna L D, Higginbotham, Henry C J et al (2000) Feline non-ocular melanoma- a retrospective study of 23 cases (1991-1999). J Fel Med Surg 2 (4), 173-181 PubMed.
- Betton A, Healy L N, English R V et al (1999) Atypical limbal melanoma in a cat. JVIM 13 (4), 379-381 PubMed.
- Roels S, Tilmant K & Ducatelle R (1999) PCNA and Ki67 proliferation markers as criteria for prediction of clinical behavior of melanocytic tumors in cats and dogs. J Comp Pathol 121 (1), 13-24 PubMed.
- van der Linde-Sipman J S, de Wit M M, van Garderen E et al (1997) Cutaneous malignant melanomas in 57 cats: identification of (amelanotic) signet-ring and balloon cell types and verification of their origin by immunohistochemistry, electron microscopy, and in situ hybridization. Vet Pathol 34 (1), 31-38 PubMed.
- Day M J & Lucke V M (1995) Melanocytic neoplasia in the cat. JSAP 36 (5), 207-213 PubMed.
- Miller W H Jr., Scott D W & Anderson W I (1993) Feline cutaneous melanocytic neoplasms: a retrospective analysis of 43 cases (1979-1991). Vet Dermatol 4 (1), 19-26 VetMedResource.
Other sources of information
- Vail D M, Withrow S J, Page R L (2013) Melanoma. In: Small Animal Clinical Oncology. Eds S J Withrow & E G MacEwen. 5th edn. Philadelphia: W B Saunders Co. pp 321-334.
- Miller P E & Dubielzig R (1996) Ocular tumors. In: Small Animal Clinical Oncology. Eds S J Withrow & E G MacEwen. 2nd edn. Philadelphia: W B Saunders Co. pp 421-431.
- Carpenter J L, Andrews L K & Holzworth J (1987) Tumors of the melanogenic system. In: Diseases of the Cat, Medicine and Surgery. Ed J Holzworth. Philadelphia: W B Saunders Co. pp 579-583.