Malignant peripheral nerve sheath tumors (MPNST) cause fusiform or eccentric swelling of the originating nerve trunk. The tumor may spread both proximally and distally causing thickening of the nerve. When arising in the setting of neurofibromatosis 1, MPNSTs are usually deep-seated. They are large (usually >5 cm), fleshy, tan-white and have foci of necrosis and hemorrhage. This is a wide-resection specimen of MPNST involving left hemi-pelvis from a 45 y/o male.