The authors report a 58-year-old woman with low-grade fibromyxoid sarcoma primarily located in the right paravertebral area with extension to L4 neural foramen. The patient complained lower back pain with radiating pain along the posterolateral aspect of the right lower leg. She underwent subtotal surgical removal and Cyber Knife therapy. Diagnosis was made by strikingly characteristic microscopic appearance of a bland spindle cell sarcoma which contained numerous giant collagen rosettes and was also supported by immunohistological findings. The diagnostic image findings and literatures are reviewed and discussed.