Osseous erosion by herniated nucleus pulposus mimicking intraspinal tumor: a case report
© The Author(s) 2010
Received: 24 November 2009
Accepted: 1 November 2010
Published: 20 November 2010
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.
KeywordsHerniated nucleus pulposus Scalloping Erosion
Increased intraspinal pressure exerted by an expanding mass such as a slow-growing intraspinal tumor is a common cause of erosion (scalloping) of the posterior vertebral wall [1–8]. As for other causes of scalloping, communicating hydrocephalus, Marfan syndrome, Ehlers–Danlos syndrome, ankylosing spondylitis, neurofibromatosis, achondroplasia, Morquio syndrome, Hurler syndrome, acromegaly, tuberculosis, and fungal infections have been reported [4, 8–15]. Erosion of the spinal osseous structure by herniated nucleus pulposus (HNP) has rarely been reported. Only 10 HNP cases with scalloping have been reported in the pertinent English-language literature [16–20].
We describe an uncommon case of HNP causing erosion of the vertebral body, the pedicle, and the lamina, which was initially diagnosed to be a tumorous lesion located in the spinal canal.
The patient was an 81-year-old woman with 3-year history of low-back pain and left leg radiating pain. Her symptoms had gradually worsened until she was not able to walk unaided. Finally, she was referred to our hospital for surgical intervention.
Neurological examination showed a positive straight-leg raising test at 20° and positive femoral nerve stretching testing on the left side. Muscle weakness found in the left quadriceps was 4-/5, and that of the left tibialis anterior was 4/5. Hypoesthesia was noted in the left leg at the L4 area.
Because of the long clinical history and the MR images, we considered the tumor to be not malignant, but rather most likely to be an HNP, and therefore did not perform biopsy prior to removing it. However, we should have done a biopsy for differential diagnosis of slow-growing malignant tumors to ensure safer treatment.
It is well known that increased intraspinal pressure exerted by an expanding mass such as an intraspinal tumorous lesion may cause erosion (scalloping) of the spinal osseous structures. Ependymoma, dermoid cysts, epidermoid cysts, schwannoma, lipomas, and lymphomas frequently show thinning of laminae and pedicles [4, 7, 8, 20]. Dural ectasia, associated with inherited disorders such as Marfan syndrome, and Ehlers–Danlos syndrome, and neurofibromatosis is also a cause of scalloping of vertebral bodies [4, 8, 9, 11, 12, 15]. There have been few reports, however, of scalloping of the spinal osseous structures caused by HNP.
Summary of the characteristics of previous cases
Sex, age (years)
Location of herniation
Location of scalloping
Vadala et al. 
More than 1 year
Norfray et al. 
Briceno et al. 
Vertebral body and pedicle
Flak et al. 
Berthelot et al. 
Yoshioka et al.
Vertebral body, pedicle, and lamina
Several authors have advocated that long clinical history of pain and chronic pressure due to large-size HNP could cause bone erosion [16–20]. Nine of the 11 cases reported so far, including the present case, had history of pain longer than 1 year (Table 1). Vadala et al.  also suggested that old HNPs might cause a mechanical irritating action on the small vascular structures of the bone cortex. Additionally, our patient was an 81-year-old woman with overt osteoporosis. We supposed that an elderly patient with osteoporosis suffering for a long period from pain caused by an HNP was likely to show erosion of spinal osseous structures.
Conflict of interest
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