Uterus-like mass of müllerian origin in the lumbosacral region causing cord tethering

The presence of müllerian-origin tissue in the lumbosacral region is extremely uncommon. The authors report two cases of müllerian-origin tissue in that region. In the first case a 33-year-old woman harbored a conus medullaris mass lesion. Spinal dysraphism, tethered cord syndrome (TCS), and diastematomyelia were also present. In the second case a 24-year-old woman presented with low-back pain and a conus medullaris lesion, which was a cause of the TCS. Pathological examination in both cases revealed a uterus-like structure with evidence of fresh and old hemorrhage. The rarity of this lesion and its association with diastematomyelia requires documentation.