Ecchordosis physaliphora presenting with cerebrospinal fluid leak and meningitis: illustrative case.

backgroundEcchordosis physaliphora (EP) is a rare notochordal remnant and the benign counterpart to chordomas with the same cell of origin. They are most commonly located intracranially along the posterior clivus in the prepontine cistern. EPs are typically discovered incidentally, but a small subset can present with symptoms, including a CSF leak. There are very few reported cases of EP-related meningitis, which occur after a short course of CSF leakage. OBSERVATIONS: A 48-year-old female with a history of clear rhinorrhea for several years presented with meningitis and a neurological decline. Neuroimaging identified a clival mass and associated bony defect between the sphenoid sinus and prepontine cistern. She was treated with antibiotics and CSF diversion via a lumbar drain. An endoscopic endonasal resection and skull base repair was performed after CSF sterilization. Neuropathological evaluation demonstrated an EP. She recovered to baseline and remains without a recurrent CSF leak or meningitis in outpatient follow-up. LESSONS: This is the first case of long-standing rhinorrhea and presentation of meningitis from a clival lesion, and it is one of the few cases of EP-related meningitis. Early recognition and workup of CSF rhinorrhea is critical to avoid progression to meningitis, and EPs are a rare cause of this presentation. https://thejns.org/doi/10.3171/CASE25540.