Cauda equina syndrome as the initial presentation of uveal melanoma metastasis

Uveal melanoma extension to the central nervous system (CNS) is exceedingly rare, and can occur through optic nerve invasion. We report a rare clinical case that presented with cauda equina syndrome as the initial manifestation of metastasis of choroidal melanoma, and showed neurotropic extension by histopathology. Our patient did not demonstrate any evidence of systemic metastasis otherwise. A 60-year-old male patient with treated choroidal melanoma in his right eye, with presumed clinical control, developed radiation-induced neovascular glaucoma refractory to medical therapy. The eye required enucleation for pain control. One month post-enucleation, he presented to the emergency department with severe abdominal pain, urine retention, constipation, and leg weakness. Magnetic resonance imaging (MRI) of the spine showed extensive leptomeningeal involvement along the entire spinal cord and the cauda equina. On further inquisition, the patient noted prior visual field defect in the contralateral eye. Brain MRI revealed intracranial metastasis with chiasmal involvement. The patient underwent radiotherapy for the brain and spine to improve his symptoms, and was ultimately transferred to palliative care. Optic nerve invasion in uveal melanoma may lead to neurotropic spread of melanoma cells with risk of intracranial and spinal cord metastasis. Neurological symptoms should raise the suspicion of clinicians regarding this complication, which is associated with increased melanoma-related mortality.