Chondrosarcomas are malignant cartilaginous neoplasms with diverse morphological features and clinical behavior. They account for about 20% of all primary malignant tumors of the bone . They usually arise in the pelvis or long bones . Primary or conventional chondrosarcoma arises in preexisting normal bone and is distinguished from the rarer secondary tumors, which occur in a preexisting enchondroma or osteochondroma . Conventional chondrosarcoma which accounts for 85–90% of chondrosarcomas is subdivided into the central, periosteal and peripheral subgroups . Non-conventional chondrosarcoma variants include clear cell chondrosarcoma, mesenchymal chondrosarcoma and dedifferentiated chondrosarcoma . The radiographic features of chondrosarcoma are often very characteristic, and a definitive diagnosis can usually be made by imaging examination alone.
Primary central chondrosarcoma is the third most common primary malignancy of bone after myeloma and osteosarcoma. Chondrosarcoma is a tumor of adulthood and older age. The majority of patients are older than 50 years of age at diagnosis, with a slight male predominance . The most common locations of involvement of chondrosarcoma include the bones of the axial skeleton (pelvis, scapula, sternum, and ribs) followed by the proximal femur and proximal humerus . Involvement of the hands and feet is rare.
Chromosomal anomalies detected in some types of chondrosarcomas include 9p21, 10, 13q14, and 17p13. Chromosomal structural abnormalities and genetic instability are reported in well-differentiated chondrosarcomas analyzed by cytogenetics. Moreover, the amplification of MYC and AP-1transcription factors plays a vital role in the pathogenesis of chondrosarcoma .
Chondrosarcomas are large tumors, usually greater than 4 cm in size . They have a translucent lobular, blue-grey or white cut surface corresponding to the presence of hyaline cartilage. There may be areas containing myxoid or mucoid material and cystic changes. Yellow-white chalky areas of calcium deposit are commonly present (mineralization). Erosion and destruction into soft tissue may be seen.
Chondrosarcomas show abundant blue-grey cartilage matrix-production. Irregularly shaped lobules of cartilage varying in size and shape are present. These lobules are separated by fibrous bands or permeate bony trabeculae. Calcified areas suggesting the presence of a pre-existing enchondroma can often be found. The chondrocytes are atypical, with variable size and shape and contain enlarged hyperchromatic nuclei. Binucleation is frequently seen. Chondroid matrix liquefaction or myxoid changes is a common feature of chondrosarcomas. Necrosis and mitoses can be seen. There is often permeation into the cortical bone and the marrow space with entrapment of bony trabeculae .
Grading of chondrosarcomas is essential and is useful in predicting histological behavior. Chondrosarcomas are divided into three grades based upon their histopathology:
Other less common types of chondrosarcomas are mesenchymal and clear cell chondrosarcomas .
Only a small percentage of the IDH1 mutations (20%) can be identified using a specific IDH1 R132H antibody.
Local swelling and pain are the most common presenting symptoms. The symptoms are usually of long duration (months to years). Tumors located in the skull base can cause neurological symptoms.
Plain radiography is used for initial evaluation. Plain X-rays allow the identification of the cartilaginous nature and the aggressiveness of the lesion . Plain X-rays may reveal the following findings:
Computed tomography scan:
Computed tomography scan can reveal the following findings :
Magnetic resonance imaging:
Tissue biopsy is essential to diagnose chondrosarcoma and differentiate it from other malignant or benign bone tumors. Biopsy should be taken from the most aggressive portion of cancer as determined by imaging.
Location and histologic grade determine the treatment approaches of chondrosarcoma. The primary treatment modality of chondrosarcoma is surgical excision. Low-grade central chondrosarcoma can be treated with intralesional curettage, burring and surgical adjuvant application such as hydrogen peroxide .
Tumors with intra-articular or soft tissue involvement, larger tumors, axial or pelvic tumors must be treated with wide excision. For the intermediate or high-grade chondrosarcoma, wide en bloc excision is the surgical approach of choice .
Chemotherapy is generally not efficient in conventional chondrosarcoma. However, it may have a role in dedifferentiated chondrosarcomas containing a high-grade spindle cell component .
After incomplete resection of high-risk chondrosarcomas, radiation therapy is indicated to improve the high local failure rates. These indications include locally recurrent tumors intermediate to high-grade tumors, and tumors in locations where surgical resection is challenging or limited. Definitive radiation can also be indicated for unresectable tumors .
Histological grade is the single most important predictor of local recurrence and metastasis. Low-grade chondrosarcomas, which grow insidiously and rarely metastasize, have a good prognosis. The 5-year survival of grade I chondrosarcomas is 83%. High-grade chondrosarcoma and dedifferentiated chondrosarcoma, by comparison, have an inferior prognosis due to the rapid growth of the tumor and the propensity for early metastasis . The 5-year survival of grade II and III chondrosarcomas is of 53% .
Patients and their families need to be educated on how to recognize the early signs and symptom of bone tumors. Patients with signs of bone pain, swelling of bones or joints, any palpable mass found on the bones, should seek early intervention. Treatment of chondrosarcoma is mainly surgical. Local recurrence can occur after surgery, so long term follow-up is recommended to monitor these patients closely.
Chondrosarcoma is ideally managed by a multidisciplinary team that consists of orthopedists, radiologists, surgical oncologists, oncologists, and pathologists. Correlation between gross, radiographic, and microscopic features of the lesion is crucial to establish the definitive diagnosis of chondrosarcoma. Postoperatively, patients require long term follow-up due to the possibility of tumor recurrence and distant metastases. The prognosis for patients with low-grade disease is excellent.
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