Malignant peripheral nerve sheath tumour of the spinal accessory nerve.

A 50-year-old man presented with a left-sided neck mass. Clinical examination revealed a large fluctuant 7 cm x 7 cm mass in the left posterior triangle. Magnetic resonance imaging (MRI) revealed an encapsulated soft tissue lesion. He underwent exploration of the neck and a 14 cm by 8 cm mass enfolding the accessory nerve was identified and completely excised. Histological examination of the surgical specimen showed features in keeping with a malignant peripheral nerve sheath tumour (MPNST). We present the clinical and pathological features of this condition.