Human tail with noncontiguous intraspinal lipoma and spinal cord tethering: case report and embryologic discussion.

Children born with a tail-like appendage have a rare malformation that is frequently associated with abnormalities of the spine and spinal cord. A contiguous fibrolipoma is usually seen extending from the subcutaneous portion of the tail into the inferior spinal cord, resulting in tethered cord syndrome. We present the case of a child born with a tail and intraspinal lipoma that were not contiguous with each other, and were separated by an intact layer of lumbosacral fascia. The tail and lipoma were removed and the spinal cord untethered, and the child is neurologically normal 2 years after surgery. The absence of a contiguous lipoma from the tail to the spinal cord suggests that this condition may be principally caused by a disorder of secondary neurulation and/or regression of the normal embryonic tail bud. The embryology of the lower spine is reviewed and possible etiologies discussed.