Melanocytic tumours of the nasal planum in cats: 10 cases (2004-2019).

Abstract

OBJECTIVES: To better characterise signalment, biologic behaviour, and treatment outcome in melanocytic tumours of the nasal planum in cats. MATERIALS AND METHODS: Retrospective study in cats diagnosed with histopathologically confirmed melanocytic tumours on the nasal planum. RESULTS: Ten cats were identified with melanocytic tumours of the nasal planum. Pigmentation of the nasal planum seemed to be a predisposing factor. Seven cats were diagnosed histopathologically with a malignant melanoma, three with a benign melanocytoma. One of the cats developed a lymph node metastasis despite diagnosis of a well-differentiated melanocytic neoplasia. In four cases, a pigmented mass, which was initially stable over a long time, showed a sudden rapid progression suggesting malignant transformation. Treatments included hypofractionated radiation therapy (n = 6) and surgical resection (n = 1). In three cats no further treatment was pursued. Complete (n = 3) and partial (n = 3) remissions were observed in cats treated with radiation therapy; however, all experienced tumour progression or recurrence after a short period of time. Most of the cats (n = 7) had to be euthanased due to tumour progression (median survival time: 265 days). CLINICAL SIGNIFICANCE: The present case series provides insights in clinical presentation and clinical outcomes of cats with melanocytic tumours of the nasal planum.