Cystic Clival Chordoma Presenting With Cerebrospinal Fluid Rhinorrhea: A Case Report and Literature Review.

Chordomas are rare malignant tumors that typically arise at the skull base and rarely present with cerebrospinal fluid (CSF) rhinorrhea. We report the case of a 40-year-old man with a clival chordoma who initially presented with headaches and serous rhinorrhea. Imaging revealed a non-enhancing cystic lesion extending from the prepontine cistern to the sphenoid sinus. Endoscopic endonasal removal of the cystic lesion and dural reconstruction was performed. Histopathology of the lesion confirmed a conventional chordoma, with positive brachyury and preserved nuclear SMARCB1 staining. The diagnosis was based on the surgical findings and histological analysis, including the Ki-67 labeling index and bone invasion. The patient recovered uneventfully and has remained free of both tumor recurrence and CSF rhinorrhea for more than two years. This case highlights the importance of including chordomas in the differential diagnosis of CSF rhinorrhea due to clival cystic lesions. It also emphasizes the critical role of histopathological examination in distinguishing chordomas from other clival lesions, such as ecchordosis physaliphora (EP). Gross total resection (GTR) should be performed when feasible, and histologic evidence of bone invasion can be an important diagnostic clue for chordomas.