summary Malignant Peripheral Nerve Sheath Tumors, also known as neurofibrosarcoma or malignant schwannoma, are malignant tumors that may occur as solitary lesions or be associated with neurofibromatosis. The condition usually presents in patients between 20 and 50 years old with soft-tissue masses associated with a peripheral nerve or prior neurofibroma. Diagnosis is made with a biopsy showing spindle cells with wavy nuclei resembling fibrosarcoma. Immunostaining is positive for S100. Treatment is usually wide surgical resection and radiation. Epidemiology Demographics 30 to 55 years for solitary neurofibromas 20 to 40 years for neurofibromatosis type 1 (NF-1) Etiology Genetics most cases associated with NF-1 4% incidence in these patients Presentation Presentation soft-tissue mass most arise from large nerves (sciatic, brachial plexus) motor and sensory deficit of the affected nerve Imaging Radiograph usually normal or non-specific soft-tissue mass MRI low-intensity on T1-weighted images high intensity on T2-weighted images serial MRI may show enlargement of previous benign nerve sheath lesion suggesting malignant transformation Bone scan mildly positive Studies Histology classic characteristics are spindle cells with wavy nuclei resembling fibrosarcoma Immunohistochemistry positive S100 stain keratin staining is negative Treatment Operative wide surgical resection + radiation indications standard of care in most patients in general, treated as high-grade sarcoma technique wide resection should include entire affected nerve radiation perform preoperative neo-adjuvant radiation chemotherapy not useful Prognosis Survival for solitary lesion is 75% (5-year survival) Survival associated with NF-1 is 30% (5-year survival)
QUESTIONS 1 of 3 1 2 3 Previous Next Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ04.178) A 45-year-old man presents for evaluation of 6 months of radicular buttock pain. A MRI is shown in Figure A. The resected mass stains positive for S100 and the histology is shown in Figures B. What is the most likely diagnosis? QID: 1283 FIGURES: A B Type & Select Correct Answer 1 Schwannoma 32% (761/2356) 2 Liposarcoma 5% (107/2356) 3 Lipoma 0% (6/2356) 4 Malignant peripheral nerve sheath tumor 61% (1433/2356) 5 Giant cell tumor of tendon sheath 2% (40/2356) L 4 Question Complexity D Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic