10148-RC-3 A case of cervical chordoma associated with USP9X gene abnormality

Abstract Introduction USP9X gene abnormalities are rare genetic disorders associated with X-linked intellectual disability and brain malformations. However, co-occurrence with chordoma has not been previously reported. We report a case of cervical chordoma in a child with a USP9X gene abnormality. Case A 12-year-old girl with a history of intellectual disability, micrognathia, cleft palate, corpus callosum hypoplasia, cerebellar hypoplasia, ventricular enlargement, central precocious puberty, diaphragmatic and inguinal hernias was diagnosed with a USP9X gene mutation at age 9. She developed left neck pain five months prior to presentation, followed by torticollis and bilateral upper limb numbness. Imaging revealed a cervical epidural tumor extending from C3 to C5, encasing the vertebral artery, and invading the spinal canal and surrounding the trachea and esophagus. Due to spinal cord compression and neurological symptoms, posterior decompression and tumor resection with laminoplasty were performed. Postoperative cerebrospinal fluid leakage required repair surgery on day 14. Histopathology confirmed chordoma. One month later, imaging showed tumor regrowth compressing the trachea and esophagus. Additional tumor resection via anterior approach was performed after vertebral artery occlusion. Discussion and Conclusion The USP9X gene encodes a deubiquitinating enzyme involved in neuronal development. Reported phenotypes include characteristic facial features, cleft palate, polydactyly, brain malformations, and pigmentation abnormalities. Although USP9X has been implicated in tumorigenesis, its association with chordoma or CNS tumors has not been established. This is the first report of a cervical chordoma in a patient with a USP9X mutation. While the causal relationship remains unclear, this case highlights the need for further investigation into possible oncogenic roles of USP9X abnormalities.