Metastatic melanoma in a Saanen goat: clinical, ultrasonographic and anatomopathological aspects - case report

Abstract

This report describes clinical, ultrasonographic and anatomopathological findings in a case of metastatic melanoma in an adult Saanen goat. Clinically, the goat had apathy, an intra-abdominal palpable firm structure, and exophytic keratinized areas on the skin of the udder. Ultrasound revealed non-encapsulated oval structures, with heterogeneous echogenicity and marked central and peripheral vascularization, and hypoechoic hepatic multifocal to coalescent areas. In the udder, there were non-encapsulated oval structures with heterogeneous echogenicity and hyperechoic center surrounded by hypoechogenic tissue. Grossly, there were black multifocal to coalescent areas in the liver, as well as black nodules in mammary and mesenteric lymph nodes, uterus, spleen, and myocardium. Microscopically, multifocal melanocytic neoplastic proliferation was observed in the dermis and junction of the udder epidermis. Most of the neoplastic cells had cytoplasmic granules of melanin. In the liver there were areas of neoplastic tissue compressing the adjacent parenchyma, with central foci of necrosis, mild desmoplasia, and multifocal infiltration of malignant cells into the adjacent tissues. Similar findings were observed in the mammary and mesenteric lymph nodes, uterus, spleen, and myocardium, which characterized metastatic melanoma. Ultrasonography played a key role for establishing the diagnosis of a metastatic melanoma and helped establish a proper clinical management protocol.