Zeitschrift für Wirbelsäule

A Case of a Primary Radiation-Induced Malignant Peripheral Nerve Sheath Tumor in the Cauda Equina in a Patient with Neurofibromatosis Type 2

Abstract

Takafumi Mitsuhara, Satoshi Yamaguchi, Masaaki Takeda, Kuniki Eguchi, Mizuki Morishige, Kazuhiko Sugiyama and Kaoru Kurisu

Background: Radiation-induced malignant peripheral nerve sheath tumors (MPNSTs) may occur in any irradiated area of the body where primary malignant lesions existed. However, there have been isolated reports regarding the radiation-induced transformation of spinal schwannomas into MPNSTs in patients with neurofibromatosis type 2 (NF2).
Case material: A 47-year-old woman presented with gradually progressive paraparesis, bowel-bladder dysfunction, and acute consciousness disturbance. Fifteen years previously, she had undergone radical hysterectomy with adjuvant intraoperative para-aortic radiotherapy for the treatment of uterine cervical cancer. Magnetic resonance (MR) images of the brain revealed hydrocephalus and multiple intracranial tumors in bilateral oculomotor and vestibular nerves. Spinal MR images revealed numerous tumors in the cervical cord and cauda equina. Signal alteration in the lumbosacral vertebral bodies on MR images, which implies fatty degeneration, suggested that the cauda equina was included in the previous radiation field. Because the patient complained of severe pain in the lower back region and lower extremities, we partially resected the lumbosacral tumors to achieve pain control. Histological examination of the resected tumors revealed the lesions to be MPNSTs. Despite postoperative radiation therapy, the residual tumor regrew. The patient is now under palliative care.
Conclusion: We report a rare case of a primary MPNST in the cauda equina occurring 15 years after the administration of intraoperative irradiation for uterine cancer. In patients with NF2 who undergo irradiation for malignancies, long-term observation is mandatory because tardive malignant transformation may occur in pre-existing schwannomas in the irradiated field.