Sacral myolipoma with involuntary contraction causing tethered cord syndrome: illustrative case

BACKGROUND: Spinal lipomas sometimes involve various ectopic tissues originating from the ectoderm, mesoderm, and endoderm in the process of morphological development. OBSERVATIONS: A 29-year-old male patient with myolipoma of the conus medullaris at the S2 and S3 levels was described. The unusual finding, involuntary muscle contraction, was presented in an operative video and a literature review. In the present case, sacral myolipoma with involuntary contraction caused tethered cord syndrome in adulthood, and untethering surgery resolved continuous buttock and leg pain. LESSONS: This rare finding is considered a surgical indication for adult patients with myolipoma.