The patient went on to have CT guided core biopsies of the lesion
Microscopic Description: Sections show several core biopsies involved by malignant spindle cell neoplasm. The tumor cells are arranged in vaguely fascicular pattern. Mitotic figures are easily identified. A subendothelial infiltrative arrangement of tumor cells is evident in some areas.
Final Diagnosis: Sacral mass, core biopsies: malignant peripheral nerve sheath tumor, high grade.