Malignant peripheral nerve sheath tumors (MPNSTs) are uncommon and aggressive soft-tissue sarcomas. They are difficult to manage due to their aggressiveness and limitations in early diagnosis and management. Complete surgical resection with or without adjuvant radiotherapy is the most effective treatment for patients with primary disease, whereas in those with metastatic disease, cytotoxic chemotherapy is beneficial. We herein present the case of a woman who complained of severe lower back pain. Computed tomography and magnetic resonance imaging revealed multiple bone and lung lesions. The patient underwent a bone lesion biopsy and was diagnosed with an advanced MPNST, which was appropriately treated with systemic chemotherapy.