A case report on a novel use of intraoperative Intrabeam™ radiation therapy for a recurrent malignant peripheral nerve sheath tumor with sciatic nerve involvement

BACKGROUND: Malignant peripheral nerve sheath tumors (MPNST) are sarcomas that arise from peripheral nerves. They generally have a poor prognosis which is exacerbated by high local recurrence rates. This case report discusses the treatment of a patient with a MPNST with local recurrence. This case report is novel due to the use of intraoperative Intrabeam™ (Zeiss, Dublin, CA) radiation therapy use in the protection of neurovascular structures such as the sciatic nerve. CASE PRESENTATION: The patient was a 65-year-old male who noticed a right posterior thigh mass slowly increasing in size over two months. A planned positive margin wide-resection excision was performed due to sciatic nerve abutment. The mass was determined to be a MPNST via postoperative pathology with positive margins along the sciatic nerve. The patient began adjuvant radiation therapy to the upper and lower thigh fields over a period of three months. Thirty-two months later, the patient was found to have a hypermetabolic mass with venous congestion and hyperemia at the prior surgical site which was confirmed by core needle biopsy to be local recurrence of the MPNST. Re-excision of the tumor was planned and performed followed by intraoperative Intrabeam™ radiation therapy. At two years of follow-up, the patient was doing well with minimal pain in his right buttock region with no new or recurrent neurological deficits. Radiologic imaging was negative for local recurrence of the MPNST. CONCLUSION: We believe this case report demonstrates a novel treatment strategy for sarcoma management. The unique use of intraoperative Intrabeam™ radiation therapy, which had not previously been used for this indication, may be efficacious in cases involving neurovascular structures. In this case, focal radiation from the intraoperative Intrabeam™ radiation device was used in a way to affect the recurrent tumor yet protect the sciatic nerve.