Journal of Postgraduate Medicine Medknow Publications and Staff Society of Seth GS Medical College and KEM Hospital, Mumbai, India ISSN: 0022-3859 EISSN: 0972-2823 Vol. 54, Num. 1, 2008, pp. 37-38

Journal of Postgraduate Medicine, Vol. 54, No. 1, January-March, 2008, pp. 37-38

Images In Radiology

Chordoma: A rare presentation as solitary ivory vertebra

Kumar S, Hasan R

Department of Radiodiagnosis, J.N.M.C.H, AMU, Aligarh, UP-202 002
Correspondence Address:Department of Radiodiagnosis, J.N.M.C.H, AMU, Aligarh, UP-202 002, drsandeeps1@rediffmail.com

Date of Submission: 26-Jan-2007
Date of Decision: 27-Jun-2007
Date of Acceptance: 29-Jun-2007

Code Number: jp08011

A 30-year-old male patient presented with low back pain for one year with gradually progressive weakness of both lower limbs for two months, more marked on the right side. There was no history of any trauma or fever. There was no history of bowel / bladder involvement. On examination he had power of 4/5 in the left lower limb and 3/5 in the right limb, with no associated sensory impairment. Plain X-ray lumbar spine (AP view) revealed diffuse osteosclerosis of L4 vertebra (′ivory vertebra′) with preserved bony contours and maintained intervertebral disc height [Figure - 1]. Computed tomography (CT) scan lumbar spine revealed diffuse osteosclerosis in the body of the L4 vertebra with an associated large soft tissue mass centered posterolaterally, more so on the right side, showing areas of low attenuation within. Small specks of amorphous calcification were seen anterolaterally within the soft tissue mass [Figure - 2]. On magnetic resonance imaging (MRI) the involved vertebra was markedly hypointense on T1W images and showed heterogeneously hypointense signals on T2W images. Adjacent intervertebral discs were normal in height and signal characteristics. The lobulated hyperintense soft tissue mass showed prominent septations within, centered posterolaterally on the right side, with craniocaudal extension of one vertebra length [Figure - 3a],[Figure - 3b]. The soft tissue mass was seen displacing the paraspinal and psoas muscles and extending into the spinal canal [Figure - 4]. A differential diagnosis of chondrosarcoma, chordoma and lymphoma was made. CT-guided fine needle aspiration cytology was done and the final diagnosis of chordoma was made [Figure - 5]. Subtotal tumor removal with adjunct radiotherapy was planned for management, but the patient refused and was lost on follow-up.

Discussion

Chordoma is a rare neoplasm of notochordal origin with an estimated incidence of 0.51 cases per million, ^[1] occurring usually at the extreme ends of the vertebral column, namely skull base and sacrococcygeal region.

Chordomas are slow-growing, locally invasive malignant tumors. The most striking radiographic feature of chordoma is central vertebral body destruction associated with a large soft tissue mass. There may be osseous expansion and osteosclerosis, especially of the vertebral end plates. In some cases osteosclerosis may predominate, resulting in an "ivory vertebral" appearance. ^[1],[2] The " ivory vertebra sign" as described on conventional radiography refers to an increase in opacity of a vertebral body, which retains its size and contours, with preserved adjacent intervertebral discs. ^[3]

The major considerations for ′ivory vertebral′ appearance are osteoblastic metastasis especially from prostate and breast, lymphoma, Paget′s disease, osteosarcoma, carcinoid myelosclerosis, fluorosis, osteopetrosis and tuberculous spondylitis in healing phase, along with rare lesions, such as chordoma, plasmacytoma, primary bone sarcomas and POEMS syndrome. ^[3],[4] However, the most likely cause for the so-called ′idiopathic′ ivory vertebra is early and asymptomatic Paget′s disease of bone. ^[4] Osteosclerosis in chordoma has been reported in 43-64% of the cases. ^[1],[5] Intervertebral disc space involvement with narrowing has been described in 11-14% of chordomas leading to adjacent vertebral involvement, a feature very unusual for a spinal neoplasm and simulates infection. ^[1],[2] On CT scan there may be solitary or multiple areas of low attenuation within the soft tissue mass, which usually has sharply defined margins. Amorphous calcifications, especially at the peripheries of the mass are another important supportive finding found in approximately 30% of spinal chordomas above the level of the sacrum. ^[1]

Since there is such diverse disease spectrum accounting for ′ivory vertebra′appearance, exhaustive investigative workup should be undertaken to segregate ominous neoplastic etiologies, which need urgent surgical management and carry poor prognosis, from benign entities which at times can be best managed conservatively with follow-up. MRI has a special role to play in the management of chordoma due to its multiplanar imaging characteristics and excellent contrast resolution. On T1 weighted images chordomas have low to intermediate signal intensity and very high signal intensity on T₂ weighted imaging. ^[1] On both CT scan and MRI, there is contrast enhancement of the mass, similar to the vascular blush being reported on angiography. ^[1]

Imaging modalities like CT scan and MRI help in delineating the exact extent of the tumor, local invasion and any systemic metastases and thus help in planning the surgery as well as defining the exact port for the adjuvant radiotherapy.

References

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