Malignant peripheral nerve sheath tumors (MPNST) are high-grade sarcomas with a tendency to local recurrences (about 40% of cases) as well as distant metastases (40% to 60% of cases) after resection. Large tumor size, positive margins, and deep location (head & neck, retroperitoneum) are adverse prognostic factors. Common sites for metastases include lung (most common), liver, brain, bones, and adrenals. The tumor may track along the nerves for considerable distances. Lymph node metastases are uncommon. The image shows a MPNST composed of high-grade spindle cells separated by collagen bundles.