Chondrosarcoma

Updated by Vincent J. Lee and Deborah A. Frassica

BACKGROUND

Chondrosarcoma accounts for what % of primary bone tumors?

Chondrosarcoma accounts for ~30% of primary bone tumors (behind osteosarcoma and multiple myeloma).

What is the most common subtype of chondrosarcoma?

Conventional chondrosarcoma constitutes 85% of chondrosarcomas. The WHO 2013 classification system has reclassified grade 1 conventional chondrosarcoma as an atypical cartilaginous tumor/chondrosarcoma grade I (ACT/CS1). Grades 2 and 3 conventional chondrosarcomas are classified as malignant due to metastatic potential.

What are some other subtypes of chondrosarcoma?

Dedifferentiated (10%), mesenchymal (<2%), and clear cell (<2%) are other chondrosarcoma subtypes, classified under the category of malignant by WHO.

How are conventional chondrosarcomas further subdivided?

Conventional chondrosarcomas are further classified by their location in bone. Most are primary central chondrosarcomas, based on their location in the medullary cavity. Secondary peripheral chondrosarcomas develop from the bone surface.

Which chondrosarcoma subtypes are typically high grade?

Conventional secondary peripheral chondrosarcoma and dedifferentiated chondrosarcoma are typically high grade. Conventional primary central chondrosarcoma can vary in grade from low to high.

What 2 precursor lesions may give rise to conventional chondrosarcoma?

Osteochondroma is a precursor lesion for conventional secondary peripheral chondrosarcoma, and enchondroma is a precursor lesion in up to 40% of conventional primary central chondrosarcoma.

Which subtypes occur in older adults? Which subtypes present in younger pts?

Dedifferentiated, conventional primary central, and conventional secondary peripheral chondrosarcoma typically present in older pts. Clear cell and mesenchymal chondrosarcoma can present in any age, but peak incidence occurs in younger adults.

What are the most common locations for conventional primary chondrosarcomas?

Most chondrosarcomas (∼75%) arise in the proximal femur, pelvis, or proximal humerus.

What are the common presenting symptoms associated with chondrosarcoma?

Conventional chondrosarcoma often presents with pain of insidious onset and progressive chronology and localized swelling.

Chondrosarcomas of the skull base typically arise from what structures?

Although chondrosarcomas of the skull base may arise from the clivus, most originate laterally from the spheno-occipital junction or less commonly from the sphenoethmoid complex.

What is the typical pattern of spread for chondrosarcoma of the skull base?

Chondrosarcomas of the skull base are locally aggressive and may expand, destroying bone and compressing adjacent tissues.

What other tumor may often be mistaken for chondrosarcoma at the skull base? How can they be distinguished histologically?

Chordoma (particularly the chondroid variant) may appear similar to chondrosarcoma. Unlike chordomas, chondrosarcomas do not express cytokeratin or epithelial membrane antigen.

WORKUP/STAGING

What are the 3 imaging tests commonly ordered for the workup of a possible chondrosarcoma?

Plain radiographs, MRI, and CT are commonly ordered for the workup of a possible chondrosarcoma. CT is best for examining tumor matrix mineralization, while MRI is best for assessing marrow and soft tissue involvement. In addition, CT C/A/P may be indicated to evaluate for metastatic Dz, particularly for high-grade histologies.

What is the characteristic plain film appearance of chondrosarcoma?

Although chondrosarcoma has a variable plain radiograph appearance, mineralization of chondroid matrix may produce a punctate or ring-and-arc pattern of calcification.

What 2 subspecialty referrals/workups should be performed prior to Tx of skull base chondrosarcoma?

Baseline neuro-ophthalmology and endocrinology workup is indicated for skull base chondrosarcoma.

What are the AJCC 7^th edition (2011) TNM stage categories for bone tumors?

T1: ≤8 cm

T2: >8 cm

T3: discontinuous tumors in primary bone site

N0: no regional LN mets

N1: regional LN mets

M0: no distant mets

M1a: lung metastasis

M1b: distant mets to nonpulmonary sites

What is the AJCC stage grouping for bone tumors?

Stage IA: T1N0, low grade

Stage IB: T2-3N0, low grade

Stage IIA: T1N0, high grade

Stage IIB: T2N0, high grade

Stage III: T3N0, high grade

Stage IVA: M1a

Stage IVB: N1 or M1b

What are the preferred techniques to confirm primary bone cancer?

Core needle or open biopsy is recommended to confirm diagnosis. Fine needle aspiration is not suitable due to lower diagnostic accuracy.

TREATMENT/PROGNOSIS

What type of surgical resection is typically recommended for chondrosarcoma?

Wide local excision (i.e., removal of tumor and a cuff of normal tissue) is typically recommended for definitive surgical Tx of chondrosarcoma. For ACT/CS1 intracompartmental chondrosarcomas, intralesional curettage followed by adj cryosurgery can be used as an alternative to WLE with acceptable outcome.

When is RT recommended for chondrosarcoma? What are the typical doses?

RT is typically recommended following incomplete resection or as palliative treatment for unresectable chondrosarcoma. Doses >60 Gy are recommended to achieve local control.

What is the recommended definitive Tx for skull base chondrosarcoma?

Maximal surgical resection is recommended for skull base chondrosarcoma. Because complete resection is generally not feasible due to anatomic constraints, adj RT is frequently recommended due to residual Dz.

What adj RT doses are necessary for control of skull base chondrosarcoma?

Adj RT doses >65 Gy are needed for control of skull base chondrosarcoma. IMRT, stereotactic RT, or charged particle therapy are modalities to consider in the effort to minimize dose to normal critical structures.

When treated with surgical resection and adj RT, what control rates can be expected for skull base chondrosarcoma?

When treated with surgical resection and adj RT (to doses >65 Gy), control rates >90% can be expected for skull base chondrosarcoma; these rates are superior to those of chordoma. (Rosenberg AE et al., Am J Surg Pathol 1999)

What role does systemic therapy play for chondrosarcoma?

Chemotherapy is not recommended for ACT/CS1 nor for clear cell chondrosarcoma. Its role is undefined for higher-grade chondrosarcomas, although there have been some reports that have advocated a role for chemo for the mesenchymal subtype.

What is a reasonable follow-up schedule for low- and high-grade chondrosarcoma?

For follow-up, consider clinical exam, local imaging, and chest imaging q6–12mos for 2 yrs, then annually for a minimum of 10 years, as relapses beyond 5 yrs are more common for chondrosarcomas than for other sarcomas.

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