Malignant anal sac melanoma in a dog

Abstract

A five-year-old female Yorkshire Terrier dog presented with a perianal mass. Fine needle aspiration revealed that the mass comprised two different types of cells: hepatoid epithelial cells and melanin-containing melanocytes. Histopathological examination confirmed perianal gland adenoma with malignant melanoma. Evidence of metastasis was found on thoracic radiography with soft-tissue densities observed within the pulmonary parenchyma. The dog survived for three months after diagnosis of malignant melanoma. This report describes the clinical findings, diagnostics used, cytological and histopathological findings, and the potential prognosis for a dog diagnosed with malignant anal sac melanoma. ? 2019, Korean Society of Veterinary Clinics. All rights reserved.