CyberKnife Radiosurgery for Spinal Leptomeningeal Metastases Secondary to Esthesioneuroblastoma: A Clinical Case Report

Esthesioneuroblastoma (ENB), also known as olfactory neuroblastoma, is a rare malignant tumor of neuroectodermal origin that arises from the olfactory epithelium. We present a case of ENB metastasizing through the leptomeningeal route to the spinal dura, which was treated with CyberKnife (CK) stereotactic radiosurgery (SRS), and aim to assess the safety and effectiveness of SRS in such cases. To the best of our knowledge, this is the first case report in the literature that discusses ENB spinal leptomeningeal metastases treated with CK radiosurgery. We retrospectively review the clinical and radiological outcomes in a 70-year-old female with ENB metastasis to the spine. Progression-free survival (PFS), overall survival (OS), and local tumor control (LTC) are investigated. In our patient, ENB had been diagnosed at the age of 58 years and spinal metastases had been first noted at the age of 65 years. A total of six spinal lesions received CK SRS. Lesions were present at the level of C1, C2, C3, C6-C7, T5, and T10-11. The median target volume was 0.72 cc (range: 0.32-2.54). A median marginal dose of 24 Gy was delivered to the tumors with a median of three fractions to a median isodose line of 80% (range: 78-81). LTC at the 24-month follow-up was 100%. PFS and OS were 27 months and 40 months, respectively. No adverse radiation effects were reported. Even though the treated spinal lesions remained stable, the number of new metastatic lesions had increased with progressive osseous and dural metastatic lesions within the cervical, thoracic, and lumbar spine at the last follow-up. SRS provides relatively good LTC for patients with ENB metastasizing to the spine, with no radiation-induced adverse events.