Cauda equina neuroendocrine tumour of the filum terminale: a rare cause of persistent sciatica

Cauda equina neuroendocrine tumours (CENETs), previously known as spinal paragangliomas (PGLs), are an extremely rare subset of spinal tumours that involve the cauda equina and filum terminale. They are classified as WHO Grade 1 and, thus, are largely benign. Their rarity, along with the overlap of their symptoms with more common spinal pathologies, leads to their frequent misdiagnosis. We present the case of a man in his mid-50s with a history of LBP exacerbated at night and right-sided sciatica with an L4 radicular distribution. He was referred to our team after being misdiagnosed and treated for lumbar disc herniation. A contrast-enhanced MRI revealed the presence of a large intradural lesion at the level of L4, treated by gross total resection (GTR) and later identified as a CENET. This case aims to enhance clinicians' understanding of CENETs, thereby preventing future misdiagnoses and improving patient outcomes.