Cerebrospinal fluid dissemination of an intracranial malignant peripheral nerve sheath tumor in the sellar region: illustrative case.

backgroundMalignant peripheral nerve sheath tumors (MPNSTs) are uncommon types of soft tissue sarcomas. The occurrence of intracranial MPNSTs in the sellar region is exceedingly rare. OBSERVATIONS: A 37-year-old female, who had undergone transnasal surgery for a pituitary adenoma followed by adjuvant stereotactic radiotherapy 10 years earlier, was diagnosed with an intracranial MPNST in the sellar region. A second transnasal procedure successfully removed the lesion and was followed by proton therapy. Three months postoperatively, spontaneous cerebrospinal fluid (CSF) rhinorrhea occurred and was repaired through a third transnasal surgery. A CSF test revealed the presence of suspicious tumor cells. Subsequently, acute hydrocephalus developed and was urgently managed with a ventriculoperitoneal shunt. About 2 months later, the patient died due to intraspinal metastasis. LESSONS: Pathologically ambiguous lesions in the sellar region require meticulous observation, as MPNST can be erroneously diagnosed as a pituitary adenoma. Prompt surgical intervention provides the best opportunity for achieving complete resection, which remains the most effective treatment for MPNST. In addition to hematogenous metastasis, MPNST can also disseminate and implant via CSF, leading to recurrence. Acute hydrocephalus or intraspinal metastasis can significantly reduce overall survival. https://thejns.org/doi/10.3171/CASE24437.