|Title : Case 620|
Age / Sex : 82 / F
Chief complaint : Foreign body sensation on the posterior neck for 4 months.
On CT, a relatively well-defined hypodense mass-like lesion with poor enhancement between the left prevertebral space and the retropharyngeal space of C2 level was observed and adjacent bone destruction was observed. The left longus colli muslce was deviated by the mass to anterolateral aspect.
On post biopsy MRI, the mass showed heterogeneous SI on T2 weighted image (WI), iso- to mild low SI in T1WI. It protruded mainly in the prevertebral space, but it was also in the C2 body, and shows an ill-defined border with the normal marrow. In the mass, the portion with T2 bright high SI showed no enhancement. The enhancement was observed along the thin wall portion which showed relatively low to mild high T2 SI on the peripheral side. The mass showed diffusion restriction. In some soft tissue of the prevertebral spaces, ill-defined T2 high SI and enhancement were observed.
Pathologically the mass was confirmed as a chondroid chordoma.
Giant cell tumor
Chordoma is a rare malignant neoplasm arising from the remnants of the primitive notochord. At gross examination, chordomas form a soft, white, multilobulated mass delineated by a fibrous pseudocapsule. The characteristic physaliphorous cells are the hallmark of chordoma. Chondroid chordoma exhibits cartilaginous differentiation, but this variation in histologic appearance does not affect the biologic behavior of the tumor. Fluid and gelatinous mucoid substance, recent and old hemorrhage, necrotic areas, and, in some cases, calcifications and sequestered bone fragments are found within the tumor. Next to lymphoproliferative tumors, chordomas are the most common primary malignant neoplasm of the spine in adults. Chordomas generally occur in late middle age, with a peak prevalence in the 5th–6th decades. Spinal chordomas have a 2:1 male-female ratio. Chordomas most commonly arise in the sacrococcygeal region (50% of cases), followed by the spheno-occipital region (35%) and the vertebral bodies (15%). Sacrococcygeal tumors usually start in the lower sacrum and coccyx. Spinal chordomas arise more frequently in the cervical spine than in the thoracic and lumbar regions. The most common site of involvement in the mobile spine is the vertebral body with sparing of the posterior elements. Clinical manifestation is often subtle because chordomas are slow-growing lesions.
The most suggestive manifestation is a destructive lesion of a vertebral body associated with a soft-tissue mass with a “collar button” or “mushroom” appearance and a “dumbbell” shape, spanning several segments and sparing the disks. Areas of amorphous calcifications are noted in 40% of chordomas of the mobile spine and in up to 90% of sacrococcygeal lesions. Most chordomas are iso- or hypointense relative to muscle on T1WI. The focal areas of hemorrhage and high protein content of the myxoid and mucinous collections that may be seen in chordomas account for the high SI on T1WI. On T2WI, most chordomas have a high SI that reflects their high water content. The fibrous septa that divide the gelatinous components of the tumor are seen as areas of low SI on T2WI. The presence of hemosiderin also accounts for the low SI seen on T2WI. Most tumors demonstrate moderate heterogeneous enhancement, but ring and arc or peripheral enhancement have also been reported.
Chordoma is a low-grade and slow-growing tumor but generally has a poor long-term prognosis despite its low tendency to metastasize. Death is often related to local recurrence. Prognosis depends on the possibility of margin-free en bloc resection. Radiation therapy may also be used as an adjunct treatment.
Chordoma should be differentiated from giant notochordal rest, which may also show physaliphorous cells at biopsy. Unlike in chordoma, radiography and CT fail to demonstrate a distinct lesion in giant notochordal rest, instead showing either normal bone or a variable degree of sclerosis. Bone scintigraphic findings are typically normal, whereas MRI shows a lesion with low T1 and high T2 SI and no soft-tissue involvement. If the lesion is found incidentally, periodic imaging studies help ensure that the lesion is not progressive with evidence of bone destruction, the occurrence of which would indicate that the lesion is malignant.
|Total applicants||21||Correct answers||6|