1249 - Not the Usual suspect: Idiopathic Epidural Lipomatosis in a Young Adult Without Obesity or Steroid Use: A Case Report

Case Diagnosis: Idiopathic Spinal Epidural Lipomatosis (SEL) in a non-obese young adult

Case Description: A 25-year-old male with no significant PMH initially presented with a 1-year history of chronic right knee pain and RLE weakness; initial X-ray of the right knee was unremarkable. Despite bracing, physical therapy, and anti-inflammatory medications, his RLE weakness worsened, ultimately developing sustained clonus in the RLE, requiring further workup. Thoracic MRI was performed, revealing significant epidural lipomatosis from T1-T10, causing spinal cord compression. He underwent T3-4 and T7-8 laminectomies for tissue evacuation. Postoperatively, he had bilateral lower extremity weakness requiring inpatient rehabilitation; rehabilitation was complicated by spasticity and bowel incontinence. At discharge, he was modified independent with bed mobility and could ambulate with a walker, had improved bowel control, and spasticity was managed with baclofen and tizanidine.

Discussions: SEL is a rare condition characterized by an overgrowth of epidural fat commonly affecting the thoracic or lumbar spine. It is more common in males than females (3:1 ratio), with an average presenting age of 43. SEL typically presents with lower extremity weakness, diminished reflexes, and sensation. Based on predisposing factors, it is categorized into five groups: exogenous corticosteroid use, endogenous steroid overproduction, obesity, prior spinal surgeries, and Idiopathic cases. SEL is diagnosed with an MRI showing adipose tissue thickening > 7mm in the epidural space, in severe cases, a characteristic “Y” sign from thecal sac compression can be seen. Treatment is dependent on the underlying etiology of symptoms, it often requires a combination of conservative approaches and surgical procedures with typically a good prognosis and functional recovery after treatment.

Conclusions: This case is an example of a rare presentation of idiopathic SEL in a young, non-obese patient without typical risk factors, underscoring the importance of keeping a broad differential including rare conditions such as SEL when investigating progressive neurological deficits despite treatment.