1. Neurofibromatosis is a disease involving both neuro-ectodermal tissues and mesodermal elements. In the past it has usually been assumed that the mesodermal abnormalities were secondary to the neuro-ectodermal ones. For example, skeletal deformities were considered to be caused by local neurofibromata.

2. It is becoming increasingly recognised that in neurofibromatosis there may be abnormal development of bone without any local abnormality of neuro-ectodermal origin. Study of our patients confirms this view. Considerable deformity of vertebral bodies was demonstrated at sites where there was no evidence of any neurofibroma or other soft-tissue change. At other sites apparent erosion of bone was associated with the formation of a local meningocele.

3. The findings in this small series of patients with neurofibromatosis suggest that the scalloping of the vertebral bodies, deformity of pedicles and widening of the intervertebral foramina are usually caused by dysplasia of bone and may be associated with a local meningocele.