Acute Transverse Myelitis Masquerading as an Intramedullary Tumor: A Diagnostic Dilemma

Acute transverse myelitis (ATM) is a rare inflammatory disorder of the spinal cord that can present as acute cauda equina syndrome (CES). Distinguishing ATM from intramedullary tumors remains a diagnostic challenge. We report the case of a 32-year-old woman with no medical history who developed acute paraplegia and urinary retention over one week. Initial MRI revealed a well-defined intramedullary lesion at D12-L1 with T2 hyperintensity and homogeneous contrast enhancement, raising suspicion of ependymoma or another spinal tumor. However, she showed rapid improvement with corticosteroid therapy, regaining sphincter control within five days and ambulation within three weeks. A follow-up MRI after one month was entirely normal, confirming the diagnosis of idiopathic ATM. This case highlights the importance of considering inflammatory causes in acute CES and the critical role of clinical and radiological follow-up in differentiating ATM from neoplastic lesions.