Malignant melanoma with central nervous system involvement in a dog treated with surgery, radiotherapy and chemotherapy

A five-year-old female entire cocker spaniel was admitted for acute obtundation and non-ambulatory tetraparesis. MRI of the brain revealed a mass lesion in the right olfactory and frontal lobe area and in the right frontal sinus. Transfrontal craniotomy was performed for surgical excision, with intraoperative application of cytarabine and methotrexate. At discharge, the dog was ambulatory with mild generalised ataxia. Histopathology and immunohistochemistry revealed a malignant melanoma. Lomustine was initiated. Six months after surgery the dog was readmitted for right exophthalmos, due to a right retrobulbar mass that was surgically excised. Histopathology confirmed melanoma, and a course of radiotherapy was added and lomustine restarted. The dog was euthanased after further 17 months for relapsing neurological signs secondary to recurrent CNS melanoma. This treatment of a melanoma with CNS involvement showed encouraging results, achieving a total survival time of 23 months.