Comparative Aspects of Canine Melanoma

Abstract

Melanomas are malignant neoplasms originating from melanocytes. They occur in most animal species, but the dog is considered the best animal model for the disease. Melanomas in dogs are most frequently found in the buccal cavity, but the skin, eyes, and digits are other common locations for these neoplasms. The aim of this review is to report etiological, epidemiological, pathological, and molecular aspects of melanomas in dogs. Furthermore, the particular biological behaviors of these tumors in the different body locations are shown. Insights into the therapeutic approaches are described. Surgery, chemotherapy, radiotherapy, immunotherapy, and the outcomes after these treatments are presented. New therapeutic perspectives are also depicted. All efforts are geared toward better characterization and control of malignant melanomas in dogs, for the benefit of these companion animals, and also in an attempt to benefit the treatment of human melanomas.

Keywords: cancer; canine; histopathology; melanoma; therapy.

Figure 1

Clinical aspect of malignant oral melanomas (A) in maxilla; (B) in mandible. Clinical aspect of malignant cutaneous melanoma (C) in thoracic and abdominal wall (Adriana Nihiya).

Figure 2

Photomicrograph of the most common histopathology type of malignant melanoma (epithelioid), showing formation of cell nests, with the presence of multinucleated giant cells and atypical mitotic figures, HE, Objective 40 × (A). Canine oral malignant melanoma, pigmented, exophytic mass protruding from the gingiva (B). Formalin-fixed tissue. Photographs are courtesy of Professor Dr. José Guilherme Xavier.

Figure 3

Photomicrograph of oral amelanotic melanoma ((A), Objective 10 ×; (B), Objective 20 ×). Hematoxylin and eosin.

Figure 4

Photomicrograph of lymph node metastasis from oral melanocytic neoplasm ((A), Objective 10x; (B), Objective 20x). Hematoxylin and eosin.

Figure 5

Photomicrograph of oral melanocytic neoplasm ((A), Objective 4 ×; (B), Objective 40 ×); Hematoxylin and Eosin.

Figure 6

Photographs showing: blackened mass in the iris with extraocular extension (A) and sagittal section of the eyeball revealing melanocytic neoplasia of iris, ciliary body, and choroid (B) (Eduardo Perlmann).