Osseous erosion by herniated nucleus pulposus mimicking intraspinal tumor: a case report

Abstract

Erosion of spinal osseous structure, so-called scalloping, has been rarely reported associated with herniated nucleus pulposus (HNP). We report a rare case of HNP causing erosion of the spinal osseous structure (including lamina). The patient was an 81-year-old woman with 3-year history of low-back pain and left leg radiating pain. Muscle weakness of the left leg was also apparent. Computed tomography following myelography showed severe compression of the dural sac at the level of L3-L4; furthermore, erosion of the lamina, pedicle, and vertebral body was noted, indicating that the space-occupying mass was most probably a tumorous lesion. The mass also showed calcification inside. During the surgery, the mass was confirmed to be an HNP with calcification. Following resection, the pain disappeared. Surgeons should be aware of the possibility of scalloping of the vertebrae caused by HNP mimicking a tumorous lesion.

Fig. 1

Plain AP and lateral radiographs of the lumbar spine

Fig. 2

CT myelography following myelography at L3–L4 showing a tumorous mass with partial calcification in the spinal canal. The right panel shows the slice corresponding to the cranial aspect of the L4 pedicle. The left panel shows the slice corresponding to the caudal aspect of the L4 pedicle. Red arrows indicate the location of scalloping, and white arrows, the calcification in the mass

Fig. 3

a MR sagittal images showing a mass at L3–L4. The mass extended caudally and strongly compressed the dural sac. b Axial MR images showing the mass located on the right side and the scalloping (red arrows)

Fig. 4

The surgical specimen shown after fixation in 10% formic acid. On macroscopic examination, it seems to be an HNP

Fig. 5

Postoperative MR images revealed that the thecal sac was totally decompressed. Scalloping was also clearly seen on postoperative MRI (arrows in the right panel)