Extramedullary-intradural spinal metastasis of small cell lung cancer causing cauda equina syndrome

Small cell lung cancer (SCLC) has a very aggressive clinical progression with widespread metastases. We describe the case of a patient with SCLC treated with concurrent chemoradiotherapy. One month later, after finishing the scheduled treatment, the patient was admitted to the hospital again with symptoms of low back pain that radiated to bilateral lower legs with painful paresthesias, urinary incontinence, and constipation. After a series of examinations, including bone scan and magnetic resonance imaging, the patient received an L2-L3 laminectomy. The concluded diagnosis through histopathologic examination with immunohistochemistry was extramedullary-intradural spinal metastasis causing cauda equina syndrome. The metastatic tumour originated from the SCLC. To the best of our knowledge, this is the first reported case of SCLC metastasized to the cauda equina causing cauda equina syndrome.