Malignant peripheral nerve sheath tumor of the cauda equina with craniospinal metastasis.

Intradural spinal malignant peripheral nerve sheath tumors (MPNST) are extremely rare, with only 20 adult patients reported to our knowledge, and only four primary tumors arising from the cauda equina. A 49-year-old man presented with back pain, constipation, and lower extremity weakness and was found to have a large intradural lesion involving the cauda equina. Imaging of the rest of his neuraxis revealed additional small left temporal lobe, cervical, and thoracic lesions. The patient underwent laminectomy for tumor debulking and biopsy, as gross total resection was not possible due to envelopment of the cauda equina. Histopathology revealed a MPNST with high cellularity, elevated proliferative indices, and nerve fascicle invasion. After the debulking, the patient reported improvement in his symptoms. However, 6 weeks later, the patient began having severe headaches, and his left temporal lobe lesion was found to have increased significantly in size, requiring craniotomy for palliative resection. The authors report the first adult patient with sporadic spinal MPNST with craniospinal metastasis to our knowledge. Imaging of the entire neuraxis is recommended for initial workup of these lesions, which are capable of intradural spread. The best treatment approach is unclear, but total surgical resection should be attempted, barring infiltration and engulfment of the nerve roots or widespread dissemination.