Expression of p53 in a malignant melanoma of a goat.

A six-year-old brown haired goat was presented due to recurring tissue growth at the base of the right horn. The tumour recurred after repeated surgical excision and the animal was finally euthanized because of poor prognosis. Necropsy revealed a malignant, partly amelanotic melanoma originating from the right horn base with metastases in both frontal sinuses, urinary bladder, pleura, pericardium, second thoracic vertebra, kidney and mesenteric lymph nodes. Diagnosis was confirmed by histopathology and immunohistochemistry. A strong expression of p53, a suppressor of cell proliferation and activator of apoptosis, was detected in numerous tumour cells suggesting an altered protein function.