MONDO_0017076 (posterior meningocele) is a rare neural tube closure defect characterized by the herniation of a cerebrospinal fluid-filled sac, that is lined by dura and arachnoid mater, through a posterior spina bifida and covered by a layer of skin of variable thickness, which may be dysplastic or ulcerated. The spinal cord and nerves are generally not included and function normally, although sometimes a tethered cord may be associated. They are most commonly located in the lumbar or sacral region.