Malignant Nerve Sheath Tumor of the Spinal Accessory Nerve: A Unique Presentation of a Rare Tumor Update on Peripheral Nervous System Tumors: Lesions with Epithelioid and Melanotic Features ScienceDirect Metastatic melanoma presenting as a malignant peripheral nerve sheath tumour MedCrave online Frontiers Case report: Presumptive subcutaneous malignant peripheral nerve sheath tumor with intracranial invasion and osteolysis in the posterior fossa of a dog