Metastatic cutaneous myxosarcoma in an adult horse

A 25-year-old mixed-breed equine with separate nodular cutaneous lesions in the right thoracic limb (RTL) and right ventral abdominal region was admitted to a Veterinary Hospital in Belo Horizonte, Minas Gerais. Fine-needle aspiration cytology was performed on the RTL lesion and superficial cervical lymph node, and the results were suggestive of a malignant neoplasm known as myxosarcoma. Due to the unfavorable prognosis, the animal was euthanized. Based on the macroscopic and microscopic findings, the diagnosis of metastatic cutaneous myxosarcoma was confirmed. Although rare, this tumor should be considered as a differential diagnosis for cutaneous neoplasms in this species.