Malignant (Anaplastic) Amelanotic/Hypomelanotic Melanoma in a Kurdish Gelding

We report an ۱۱-year-old Kurdish gelding with an anaplastic malignant melanoma arising from his right lateral of the neck, which developed over ۶ weeks. A ~۱۰ cm in diameter, firm, and non-ulcerated nodular subcutaneous mass located at the middle and proximal of the left side of the neck was detected in a physical examination. No evidence of local extent or metastasis was detected. Complete surgical excision was performed under general anesthesia. Gross morphology and histopathological examination of the mass confirmed an anaplastic malignant melanoma, in which the major part of the mass has little or no pigmentation. The gelding was euthanized due to tumor regrowth. The heterogeneity in pigmentation of equine melanocytic tumors can make diagnosis difficult in punch biopsy specimens. Anaplastic malignant melanoma is most often a very aggressive neoplasm and surgical excision was not effective in this case.

Keywords:

Anaplastic , Amelanotic , Poorly pigmented , Malignant Melanoma , Neck , horse