Ultrastructurally, the tumor cells are spindle-shaped, some of which show long, intertwining cell processes. There is focal basal lamina formation. The nuclei are pleomorphic with many indentations; generally one large nucleolus is seen within the tumor cells. The nuclear to cytoplasmic ratio is high. the cytoplasm contains abundant rough endoplasmic reticulum, and some mitochondria and lysosomes.
grade sarcoma, consistent with malignant peripheral nerve sheath