Expression and Significance of Inflammatory Factors in Idiopathic Spinal Epidural Lipomatosis (Grade III).

BACKGROUND: Idiopathic spinal epidural lipomatosis (iSEL) is frequently associated with the utilization of steroids, endocrine disorders, obesity, and surgical interventions. Nevertheless, the pathogenesis of iSEL remains inadequately understood. The study aimed to investigate the contribution of inflammatory factors to idiopathic epidural lipomatosis. METHODS: Thirteen patients with iSEL (Grade III, iSEL group) and 12 patients with lumbar disc herniation (control group) who underwent unilateral biportal endoscopy from March 2020 to April 2023 were enrolled. Histological examination of adipose tissue was the performed to analyze expressions of pro-inflammatory cytokines (TNF-α, IL-1β), and anti-inflammatory factors (arginase-1, IL-10) in serum and epidural adipose cells. RESULTS: Compared with the control group, the number of inflammatory cell infiltrations per field in HE-stained sections was significantly elevated, TNF-α and IL-1β expression in adipocytes of epidural adipose tissue were markedly higher, and arginase-1 and IL-10 expression were significantly lower in the iSEL group (all p < 0.001). However, no statistically significant differences were observed in the serum level of TNF-α, IL-1β, arginase-1, and IL-10 between the two groups (p = 0.963). In addition, there was also no significant disparity in adipocyte size between the two groups (p = 0.739). CONCLUSION: iSEL demonstrated elevated inflammatory cells and imbalance towards proinflammatory cytokines in adipocytes of epidural adipose tissue that may be associated with the pathogenesis of symptomatic iSEL. These data suggest that inflammatory response could be one of the mechanisms of iSEL. However, further multicenter epidemiological investigations and rigorous basic and clinical research are warranted to elucidate the specific etiology of iSEL.