A case of anaplastic malignant melanoma in a 10-year-old gray mare is described. Clinical signs included depression, progressive weight loss, fever, anorexia, and dyspnea. Multiple circumscribed or infiltrative, pigmented, and non-pigmented tumors were observed in subcutaneous tissue and in several organs. Histological examination revealed a marked variation in neoplastic cell population, which was composed by spindle, round, polyhedrical, and less frequently, multinucleated or signet ring cells. The diagnostic was based up on clinical and pathological findings, and confirmed by transmission electronic microscopy.
equine diseases; neoplasm; melanoma; pathology
