Discussion

Introduction: Malignant peripheral nerve sheath tumors (MPNST) are soft tissue neoplasms arising from peripheral nerves that arise spontaneously or with neurofibromatosis type 1 (NF1). Although metastasis is common for MPNST, very few intracranial metastases have been reported. 29 cases of intracranial MPNST metastasis have been reported in the literature, 8 in patients with NF1. All of these patients were treated with surgical resection, whole-brain radiation, chemotherapy, and/or radiotherapy with an average reported survival time of 5.9 months after diagnosis.

Methods: We present the unique case of a 60 year old female with NF1 who underwent laser interstitial thermal therapy (LITT) for metastatic MPNST of the brain.

Results: The patient presented to the ED complaining of one week of dysarthria and facial droop. MRI of the brain demonstrated a homogeneously enhancing left frontal mass; although rare, given her history of pulmonary MPNST, brain invasion was considered likely. Stereotactic needle biopsy was performed with pathology revealing a densely cellular, high grade, poorly differentiated spindle cell neoplasm consistent with MPNST. No generally accepted guidelines for the treatment of MPNST with cerebral metastases exist; however, LITT was chosen due to tumor morphology and risk of neurological deficit due to the presence of overlying eloquent structures. She did not experience any new or worsening neurological deficits postoperatively. Post-ablation MRI showed white matter edema surrounding the lesion, which is consistent with previously reported cases. Upon discharge, she was lost to follow up until she presented to the ED in status epilepticus with respiratory failure. She expired 58 days after LITT.

Conclusion : We present a rare manifestation of MPNST metastatic to the brain, and to our knowledge, the first reported use of LITT in treatment for this pathology. Using this minimally invasive approach, we were able to preserve the patient’s neurological function and did not worsen her existing neurological defects.