Chondrosarcoma



Chondrosarcoma


R. Lor Randall

Kenneth J. Hunt



Chondrosarcomas of bone can be found in any bone in the human body and include a spectrum of lesions that range from low grade to dangerously aggressive. Although cartilage bone lesions in general have a characteristic radiographic appearance, differentiating between benign and low-grade malignant cartilage lesions often presents a diagnostic challenge (Table 6.3-1). Since treatment and outcome are based in large part upon an accurate diagnosis, this distinction is important (Fig. 6.3-1).


Pathogenesis


Etiology



  • Unknown


  • Current speculation: may arise from monoclonal expansion of single chondrocyte


Epidemiology



  • Peak age: third to sixth decades (Fig. 6.3-2)


  • Frequency of chondrosarcomas in the United States



    • ∼10% to 25% of primary bone tumors are chondrosarcomas.


    • Approximately 250 to 625 cases/year in United States


    • Second to osteosarcoma among bone sarcomas








Table 6.3-1 Differentiation Between Benign and Low-Grade Malignant Cartilage Lesions


































Parameter Enchondromas Chondrosarcomas
Definition Benign cartilage tumors Malignant cartilage tumors
Metastatic potential None Increases with grade
Clinical presentation Often painless and discovered incidentally Often painful
Location Metacarpals and phalanges > long bones
Metaphyseal > diaphyseal		 Pelvis > femur > ribs > humerus > scapula > tibia
Plain radiographs Variably mineralized central lesions with arcs, smoke rings, or popcorn patterns
No or <50% cortical width endosteal scalloping		 Variably mineralized with same patterns or more punctate calcifications
Often radiolucencies with sparse mineralization
Endosteal scalloping >50% cortical width
Cortical breech with soft tissue mass in advanced cases
MRI Multilobular
Dark T1, bright T2		 Soft tissue extension and surrounding edema more common
Dark T1, bright T2
Histopathology Hyaline cartilage encased by rim of reactive bone (“enchondroma encasement” pattern)
Lobular growth
Bland chondrocytes with pyknotic nuclei
Variably cellular
Lesions of digits and those in Ollier’s disease often more worrisome in appearance (e.g., cytologic atypia and binucleation)		 Cartilage permeates around pre-existing bone trabecula (“permeation pattern”)
Invasion of haversian canals
Lobular growth
Cytologic atypia
Binucleation more prominent
Increased cellularity


Pathophysiology


Histopathology (Fig. 6.3-3)



  • Macroscopic appearance



    • Heterogeneous gross properties, including lobulated areas of chalky calcific admixture


    • Regions of firm translucent unmineralized gray cartilage with relatively low vascularity


    • Intermixed areas of necrosis and degeneration


  • Low-grade chondrosarcomas



    • Relatively acellular, heavily calcified areas


    • Regions of increased activity exhibiting immature cartilage cells with multiple nucleated lacunae


    • Permeation pattern of cartilage surrounding pre- existing bony trabeculae



  • High-grade chondrosarcomas



    • Densely packed, hyperchromatic, malignant-looking cells


    • May be difficult to determine that these cells are truly of cartilaginous origin


    • Myxomatous changes and highly degenerative areas common






Figure 6.3-1 Degree of differentiation in cartilage tumors. (Adapted from Dorfman HD, Czerniak B. Malignant cartilage tumors. In: Dorfman HD, Czerniak B, eds. Bone Tumors. St. Louis: Mosby, 1998.)


Classification



  • Several classification schemes



    • Histologic grade (I, II, III, dedifferentiated)



      • The most important factor in the malignant potential of a chondrosarcoma is its histologic grade. Most (∼85%) chondrosarcomas are low-grade lesions.


    • Location within the bone and body



      • Peripheral (periosteal or juxtacortical chondrosarcoma and secondary chondrosarcoma arising from osteochondroma) versus central (intramedullary)


      • Axial versus appendicular skeleton


    • Primary versus secondary



      • Primary: arises de novo


      • Secondary central: arises from enchondroma


      • Secondary peripheral: arises from osteochondroma


    • Specific histologic subtype



      • Conventional


      • Clear cell chondrosarcoma


      • Mesenchymal chondrosarcoma


      • Dedifferentiated chondrosarcoma


  • Histologic grades of conventional chondrosarcomas (Table 6.3-2)



    • Grade I (“low-grade”) tumors



      • Slow-growing and locally aggressive






        Figure 6.3-2 Age-specific frequency and distribution of chondrosarcoma, based on SEER 1973–1987 data. (After Dorfman HD, Czerniak B. Bone cancers. Cancer 1995;75:223–227.)







        Figure 6.3-3 Representative histopathology specimens from typical chondrosarcomas. (A) Grade I chondrosarcoma demonstrates increased cellularity, perhaps some hyperchromatism but not necessarily atypia. (B) Grade II chondrosarcoma demonstrates increased cellularity and atypia. (C) Grade III chondrosarcoma demonstrates markedly increased cellularity and pleomorphism. (D) Dedifferentiated chondrosarcoma demonstrates area of low-grade chondrosarcoma with abrupt transitions into a spindle cell sarcoma. (E) Clear cell chondrosarcoma demonstrates bony trabeculae-intertwined tumor cells containing clear cytoplasm with central atypical nuclei admixed with benign giant cells. (F) Myxoid chondrosarcoma demonstrates round cells with myxoid features. (G) Mesenchymal chondrosarcoma demonstrates nodules of chondroid tissue surrounding vascular spaces, resembling a hemangiopericytoma.









        Table 6.3-2 Clinicopathologic Features of Cartilaginous Tumors


































        Lesion Clinical Radiology Histopathology Treatment
        Enchondroma Mostly asymptomatic and incidentally recognized 9% have endosteal scalloping Enchondroma encasement pattern Surveillance, intralesional excision if symptomatic
        Chondrosarcoma
              Grade I 60% are painful Endosteal scalloping, calcifications in rings or spicules, uniform calcifications, eccentric lobular growth Chondrosarcomatous permeative pattern Controversial: Extended intralesional excision versus wide resection
              Grade II Up to 80% painful Endosteal scalloping, potentially more aggressive and adaptive changes Mixture of grade I and grade III characteristics Wide resection
              Grade III Up to 80% painful Endosteal scalloping, faint amorphous calcifications, large lucent areas, growing soft tissue mass Densely packed hyperchromatic malignant-looking cells, cells of questionable cartilaginous origin, myxomatous changes, highly degenerative areas Wide resection
        Possible adjunct radiation therapy and chemotherapy in selected cases


      • Recurrence common, but very low metastatic potential


      • Histologically resemble normal hyaline cartilage, may surround or permeate through areas of lamellar bone (a feature not seen in benign lesions, which are more typically encased by bone)


      • Radiographically may show bone expansion, cortical thinning, endosteal scalloping, periosteal reaction, lytic areas


    • Grade II (“intermediate-grade”) tumors

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Jul 21, 2016 | Posted by in ONCOLOGY | Comments Off on Chondrosarcoma

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