Chondrosarcoma
Chondrosarcomas are extremely rare, locally invasive, and potentially mortal malignant cartilaginous tumors.
The most common sites for chondrosarcoma to grow are the pelvis and shoulder, along with the superior metaphysial and diaphysial regions of the arms and legs.
However, chondrosarcoma may occur in any bone, and are sometimes found in the skull, particularly at its base.
Rare in the craniovertebral junction.
Classification
Chondrosarcoma Classification
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1. Based on Histological Grade (WHO 2020)
* Grade 1 (Low-grade chondrosarcoma)
- Rare mitoses
- Low cellularity
- Slight nuclear atypia
- Sometimes called *atypical cartilaginous tumor (ACT)* when located in appendicular skeleton
* Grade 2 (Intermediate-grade)
- Increased cellularity
- Moderate atypia
- Mitoses more frequent
- Higher risk of recurrence and metastasis
* Grade 3 (High-grade)
- High cellularity
- Significant atypia and mitotic activity
- Aggressive behavior with high metastatic potential
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2. Based on Location
* Central (medullary) – Most common * Peripheral – Often develops from osteochondromas * Juxtacortical (periosteal) – Rare, arises on bone surface
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3. Based on Histological Subtype
* Conventional chondrosarcoma (most common) * Clear cell chondrosarcoma – Low-grade, epiphyseal * Mesenchymal chondrosarcoma – High-grade, biphasic pattern * Dedifferentiated chondrosarcoma – Aggressive, with high-grade non-cartilaginous component * Myxoid chondrosarcoma – Controversial; may overlap with extraskeletal myxoid tumors
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4. Based on Anatomic Site
* Axial skeleton (pelvis, spine, skull base) – Often high-grade, worse prognosis * Appendicular skeleton (long bones) – Typically lower grade, better outcomes
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5. Based on Molecular Features
* IDH1/IDH2 mutations – Present in many central and dedifferentiated chondrosarcomas * COL2A1 alterations, CDKN2A deletions, and TERT promoter mutations – Associated with dedifferentiation and poor prognosis
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6. Extraskeletal Chondrosarcoma
* Rare, arises in soft tissues without bone involvement
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Differential diagnosis
Treatment
Standard management of chondrosarcoma involves surgical resection and adjuvant radiation therapy.
Skull base chondrosarcoma
Parafalcine chondrosarcoma
Parafalcine chondrosarcoma is extremely rare, and may be difficult to differentiate preoperatively from falx meningioma. An 18-year-old woman presented with a parafalcine chondrosarcoma incidentally detected as a small lesion 2 years before admission, suggesting falx meningioma. Brain computed tomography and magnetic resonance imaging just before admission revealed the parafalcine lesion had increased by about nine times in volume during the last 2 years. Single-photon emission computed tomography (SPECT) after intravenous administration of both thallium-201 chloride 1).
Case series
Case reports
A 25-year-old female underwent attempted endoscopic endonasal resection of an advanced right-sided chondrosarcoma. During resection of the tumor, brisk arterial bleeding was encountered consistent with focal injury to the right cavernous ICA. Stable vascular hemostasis could not be achieved with tamponade. An intravenous bolus dose of adenosine was administered to induce a transient decrease in systemic blood pressure and facilitate placement of the muscle patch over the direct site of vascular injury. The patient subsequently underwent endovascular deconstruction of the right ICA.
This is the first reported use of adenosine to induce transient hypotension for a major vascular injury sustained during endonasal skull-base surgery. Based on well-established safety data from neurosurgical application, adenosine has the potential to be used as a safe and effective adjunctive technique in similar endonasal circumstances and may represent an additional tool in the armamentarium of the skull-base surgeon. Surgeons should consider having adenosine available when a risk of ICA injury is anticipated 2).