Age / Sex : /

Age / Sex : 46/F
Chief complaint : Palpable neck mass 

chordoma

Discussion

Findings:
 On cervical spine lateral view, homogeneous increased opacity which displaces the airway anteriorly is seen at upper cervical level. The anterior cortical margin of C3 body is indistinct. And suspicious focal decreased opacity is noted in left pedicle of C3 on both AP and lateral views.
 On MRI, the lesion is located at body, left pedicle and lamina of C3. It extends to retropharyngeal space and left neural foramen, and encases left vertebral artery. So it can be called mushroom appearance on axial images, and collar button appearance on sagittal images. On T2 weighted images, the lesion shows very high signal intensity and interval septa-like low signal intensity areas. On T1 weighted images obtained after injection of gadolinium, it shows mild peripheral and septal enhancement, and the main portion remains low signal intensity.

Differential Diagnosis:
1. Chordoma
2. Chondrosarcoma
3. Neurogenic tumor
4. Metastasis
5. Lymphoma

Discussion:
1. Origin and embryology
Chordomas are locally aggressive but slow-growing neoplasms which arise from ectopic remnants of the embryonic notochord. Remnants of notochord tissues that are found outside the nucleus pulposus are referred to as benign notochordal remnants (ecchordosis physaliphora), which may persist and give rise to a chordoma. Because these rests have an intraosseous location, chordomas are usually extradural and cause local bone destruction and invasion of adjacent structures. They can occur at any level along the neural axis, but most frequently in the sacrococcygeal (50–60%) or spheno-occipital regions (25–40%), but spinal chordomas arise more frequently in the cervical than in the thoracic and lumbar regions. If the cervical spine is affected, this preferentially concerns the upper part.
2. Epidemiology
Chordoma is a relatively common tumor accounting for 3–4% of primary malignant bone tumors in major series. Chordomas are twice as frequent in men as in women, and have been reported at all ages, but the craniocervical lesions occur usually in the fourth decade
3. Clinical aspect
The cervical localization, seen in this case, is uncommon, and the clinical manifestations are not specific. Pain is the initial symptom in most cases and is caused by pressure of the tumor on extravertebral and vertebral structures. Since they respond poorly to irradiation and chemotherapy, extensive resection is desirable but often impossible because of the extent of the tumor at presentation and because of several anatomical constraints. The recurrence rates are high and the prognosis is poor with few patients surviving longer than 5 years.
4. Pathology
Microscopically the notochord tissue is somewhat similar to immature cartilage and is composed of oval cells with central nuclei and vacuolated cytoplasm embedded in an eosinophilic myxomatous stroma. The characteristic physaliphorous cells form the hallmark of chordoma. Chordoma may also exhibit cartilaginous differentiation. Areas of cartilage can range from small microscopic foci to large prominent areas. As a consequence chordomas can occasionally be difficult to distinguish from chondrosarcoma. Macroscopically, chordomas form a white, soft, multi-lobulated mass delineated by a fibrous pseudocapsule which, because of adjacent tissue compression, has the appearance of a true capsule. Fluid and gelatinous mucoid substance, associated with recent and old hemorrhages, and necrotic areas are found within the tumor, and in some cases calcification and sequestered bone fragments.
5. MR findings
The appearance of advanced lesions is that of vertebral destruction with soft tissue extension. Involvement of the Intervertebral disks, enlargement of the neural foramen, and calcified deposits are often seen. Most of the lesions exhibited a so-called collar button appearance in the sagittal plane and a dumbbell or mushroom appearance in the axial plane. The presence of a concomitant soft tissue mass, spanning several vertebral levels, is highly characteristic for chordomas and extension may occur anteriorly, laterally or posteriorly towards the epidural space. On MRI, chordomas are hypointense or isointense on T1-weighted images and are hyperintense on T2-weighted images. Septations of low signal intensity within the tumor have been reported to be present on the T2-weighted images in 70% of the chordomas. Contrast enhancement is heterogeneous but usually moderate to mark. In some cases we found a ring and arc enhancement while others showed only a peripheral rim enhancement. The pattern of contrast enhancement can reflect the pathological features of these tumors, which are organized in lobules with mucinous and gelatinous contents with cartilaginous components. And this enhancement pattern is also described in cases of chondroid tumors, such as low-grade chondrosarcoma or other chondroid lesions. Calcification of the soft tissue mass occurs in 15–18% of cases. Septations have been reported in 70% of chordomas and are, according to the literature, a characteristic feature of chordoma Neurofibroma, metastasis, lymphoma, and chondrosarcoma should be included in the differential diagnosis.

References:
1. Cervical chordoma with vertebral artery encasement mimicking Neurofibroma: MRI findings. Mortelé B, Lemmerling M, Mortelé K, Verstraete K, Defreyne L, Kunnen M, Vandekerckhove T. Eur Radiol. 2000;10(6):967-9.
2. Value of MRI in the diagnosis of non-clival, non-sacral chordoma. Smolders D, Wang X, Drevelengas A, Vanhoenacker F, De Schepper AM. Skeletal Radiol. 2003 Jun;32(6):343-50.