How is it diagnosed? Surgical removal with histopathology or incisional biopsy is required for definitive diagnosis of malignant melanoma. For tumors arising from the nail bed, radiographs of the affected toe

Malignant melanoma (MSA) is a cancer of pigmented cells called melanocytes. Cutaneous malignant melanoma may occur in the nail bed or on the foot pads. Melanomas that arise from the haired skin of the body, legs, or eyelids are usually benign but in rare cases can exhibit aggressive behavior similar to those of the nail bed, foot pads or mouth. Malignant melanoma can be a very aggressive cancer in dogs with moderate potential for metastases, or spread, to other parts of the body, particularly the lymph nodes and lungs. Early, aggressive treatment is important to improve outcome for patients with cutaneous malignant melanoma.