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Neuroradiology Case of
the Week
Case 197
Malin Cesarz , MD and Per-Lennart Westesson, MD, PhD, DDS
Clinical
Presentation:
Patient is a
81-year-old female with chronic left eye paralysis presented increasing confusion and falls for the past 2 months. The patient also complained of increasing left facial pain.
Radiological Findings:
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| Figure 1: A large mass containing calcifications can be seen occupying the left basisphenoid region, eroding through adjacent bony structures and deforming bilateral orbits. The mass extends across the midline to involve the right infratemporal fossa. |
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| Figure 2. Hypodensities of the left temporal lobe represent tumor extension upwards from the skull base to involve brain parenchyma. |
Diagnosis: Chondrosarcoma of the skull base, extending to involve the left cerebral hemisphere
Discussion: Chondrosarcomas are slow growing, locally invasive tumors that arise from cartilage, endochondral bone, or from mesenchymal cells in meninges. While they comprise only 6% of all skull base tumors, the majority of chondrosarcomas affecting the cranium are in the skull base (75%).
Clinical presentation includes cranial nerve 6 palsy and insidious onset of headache. Other cranial nerves can also be involved from mass effect. The patient age range is from 10 years old to 80 years old, although most present in middle age.
CT and MR are the main modalities used to image chondrosarcomas. On CT the typical appearance is a solitary tumor that may contain calcifications, located at the petro-occipital fissure with local bone invasion. Chondroid matrix calcification can be seen in 50% of the cases. The calcification can appear to be arc- or ring-like. The transition to normal bone is sharp and narrow. Destruction of bone is common (>50%). Enhancement is variable with contrast administration. On MR the tumor typically shows heterogeneous enhancement on T1 after contrast administration. On T2 the tumor shows high signal intensity.
The differential diagnoses of chondrosarcoma include chordoma, chondromyxoid fibroma, plasmacytoma, nasopharyngeal carcinoma, and metastases. It can be especially difficult to distinguish between chondrosarcoma and chordoma. One characteristic that can help is location. Cranial chordomas are usually in the the midline in the clivus. Chondrosarcomas are located in the petro-occipital fissure 2/3 of the time and in the anterior basisphenoid area 1/3 of the time.
Treatment of chondrosarcoma involves surgical resection with radiation therapy.
References:
- Harnsberger HR, Wiggins RH. Diagnostic Imaging Head and Neck. Canada, Amirsys, 2004; I:3-58 to I:3-61.
- Neff B, Sataloff RT, Storey L, Hawkshaw M, Spiegel JR. Chondrosarcoma of the skull base. Laryngoscope. 2002 Jan;112(1):134-9. [Medline]
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