Diagnosis

Chordoma

Findings

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.

Discussion

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.