Spinal cord tumors presenting with neural tube defects.

Two primary lumbosacral tumors arising at the site of neural tube defects are presented. One was a teratoma diagnosed in an infant with myelomeningocele. The other was an ependymoma that developed in an adult with meningocele. It is postulated that these cases represent a neoplastic transformation of heterotopic primordial elements that have been incorporated within the defect, supporting the view that overgrowth of neural tissue may be the result rather than the cause of neural tube deformity. Such rare occurrences may be due to interaction between intrauterine teratogenic factors and familial predisposition in affected patients.