Cutaneous malignant melanoma is rare in cats and in most domestic species except for dogs, in which it is common. Feline nonocular melanomas have been reported in Domestic Shorthair cats of all ages, but there is no apparent sex or color predilection. The majority of tumors occur on the head, most frequently the nares, forehead, base of ear, and pinna. Metastases are commonly found in regional lymph nodes. Treatment is primarily surgical excision, with additional therapies including radiation, chemotherapy, and vaccination. Studies involving cats are not numerous enough to make survival predictions, but poorly pigmented tumors and evidence of metastases are associated with a poor prognosis.
The tumors are derived from melanocytes that are of neuroectoedermal origin. Malignant melanoma resembles the more common benign counterpart, with less pigmentation and wide variation in cell morphology and arrangement. This variability complicates the cytologic and histopathologic diagnosis. On cytologic specimens, groups of cells may appear to be of epithelial origin (occurring in clusters) or mesenchymal origin (individual oval to spindle-shaped cells) or appear as discrete, round cells. Advances in immunohistochemical staining are helping to diagnosis poorly pigmented tumors.
Read more about
Overview of Tumor of the Skin and Soft Tissues,
Tumors of the Skin in Cats,
Tumors of Melanocytic Origin, and
Metastatic Tumors
in The Manuals.
References
Chamel G, Abadie J, Albaric O, et al. Non-ocular melanomas in cats: a retrospective study of 30 cases. J Feline Med Surg. 2107 Apr;19(4):351-357. doi: 10.1177/1098612X15625355
Hirz M, Herden C. Cutaneous amelanotic signet-ring cell malignant melanoma with interspersed myofibroblastic differentiation in a young cat. J Vet Diagn Invest. 2016 Jul;28)4:429-35. doi: 10.1177/1040638716644768
Morges MA, Zaks K. malignant melanoma in pleural effusion in a 14-year-old cat. J Feline Med Surg. 2011 Jul’13(7):532-5. doi: 10.1016/j.jfms.2011.05.011
Munday JS, French AF, Martin SJ. Cutaneous malignant melanoma in an 11-month-old Russian blue cats. N Z Vet J. 2011 May;59(3):143-6. doi: 10.1080/00480169.2011.561779
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