3 x 3 x 2.7cm mass involving the dorsum sellae centered in the
region of the left cavernous sinus, encasing the left carotid
artery. Characteristics of this mass include low signal intensity
on T1 weighted images, moderately high signal intensity on the
proton density weighted images, and enhancement on post Gad images.
Lesion exhibits mass effect on the pituitary with shift of the
gland to the right. The mass extends superiorly into the
suprasellar cistern as well as posteriorly into the retroclival
space and prepontine cistern.
Chordoma is one of the two most common primary neoplasms of the
skull base, the other being chondrosarcoma. Peak incidence is in
the 6th decade, although they may occur at any age. Chordomas are
slow growing neoplasms that result in local invasion and
destruction, although distal metastases are rare. Symptoms are
related to the actual location of the tumor, but are most commonly
due to compression of the brain stem or cranial nerve neuropathies.
Chordomas arise from notochordal rests, and may therefore occur at
virtually any location from the level of the dorsum sellae through
the coccyx. Most commonly, in approximately 50% of cases, chorcomas
occur in the sacrococcygeal region. The other 50% generally occur
in the skull base followed by the cervical spine. At the skull
base, chordomas generally occur near the midline within the clivus,
although an eccentric location may occur, making differentiation
from a chondrosarcoma necessary. MRI imaging reveals low to
intermediate signal intensity on T1, and high signal intensity on
T2 weighted images. Contrast enhancement does occur, but the degree
of enhancement is variable.
1) Orrison Jr, William W. Neuroimaging. W.B. Saunders Company,
Philadelphia, 2000. 2) Osborn, Anne G. Diagnostic Neuroradiology.
Mosby, Baltimore, 1994.