Lipomyelomeningocele with Intraspinal Cartilaginous Choristoma: A Rare Case of Heterotopic Mesenchymal Differentiation

Lipomyelomeningocele (LMMC) is a closed neural tube defect in which neural elements are incorporated into a spinal lipoma. This congenital condition may present at birth as a lumbosacral subcutaneous mass or manifest neurologic symptoms later in life. A choristoma is a tumor-like mass of normal tissue in an abnormal location, most commonly found in the head and neck, and it is exceedingly rare within the spinal canal. We report an 11-month-old female infant with a congenital lumbosacral swelling whose MRI revealed a tethered cord and LMMC with spina bifida at the S2–S3 level. Surgical detethering was performed, and histopathology confirmed LMMC. In addition, a heterotopic cartilaginous choristoma was identified in the excised tissue, an unusual finding in spinal dysraphism. This case highlights a unique example of heterotopic mesenchymal differentiation in spinal dysraphism and adds to the limited literature on intraspinal choristomas.