What is Chondrosarcoma?
Chondrosarcoma is a rare and malignant cancer which affects the joints and bones. Around 20% of brain tumors are Chondrosarcoma. Chondrosarcoma is the second most common primary cancer of the bone. Chondrosarcoma is a term which refers to a heterogeneous classification of lesions which have diverse clinical behavior and morphological features. The tumor cells in Chondrosarcoma produce a pure hyaline cartilage, which causes abnormal cartilage and/or bone growth. As in all the cancers, chondrosarcoma also has an abnormal growth where there is an abnormal growth which is a bony type of bump, which can differ in location and size.
Adults between the age of 20 and 60 years old are usually affected by Chondrosarcoma. This cancer typically begins in the bones of the arms, legs or pelvis; however, it can occur in any region of the body which has cartilage. In some cases, chondrosarcoma can also develop on a healthy bone, and chondrosarcoma can also grow on a benign bone tumor, such as osteochondroma and enchondroma.
Grades of Chondrosarcoma
- Grade-I Chondrosarcoma: These are low grade tumors, which have moderate amount of cells and has hyperchromatic plump nuclei that is of stable size. The cytology of Grade-I Chondrosarcoma resembles enchondroma. In some cases, binucleated cells can be present.
- Grade-II Chondrosarcoma: This is of intermediate grade, which consists of more cells that have greater extent of hyperchromasia, nuclear atypia and nuclear size.
- Grade-III Chondrosarcoma: These are high grade tumors which have sizeable areas of significant pleomorphism. There are large cells with more hyperchromatic nuclei with abundant necrosis and occasional giant cells. Mitoses are also frequently found.
Types of Chondrosarcoma
Chondrosarcoma can be of several types depending on the type of cells which are present in the tumor and how they appear microscopically.
- Mesenchymal Chondrosarcoma: This is an extremely malignant and aggressive tumor where there are solid cellular areas present that consist of slightly spindled or round spindled primitive mesenchymal cells. Mesenchymal Chondrosarcoma histologically resembles Ewing’s sarcoma with foci of cartilaginous differentiation. Mesenchymal Chondrosarcoma has a high risk of distant metastasis and local recurrence.
- Clear Cell Chondrosarcoma: These are low-grade tumors that contain significant amount of glycogen. The epiphyseal end of a long bone is usually involved. Histologically, there is abundant clear cytoplasm present in the cells, which is enclosed in a loose hyaline cartilaginous matrix. This tumor has an infiltrative growth pattern. Radiological tests reveal a lytic defect, which is sharply demarcated with sclerotic margins and is present at the epiphyseal end of the long bones. These tumors have a low recurrence rate and wide resection of them carries a good prognosis.
- Dedifferentiated Chondrosarcoma: This type of chondrosarcoma has two clearly differeitnatited parts along with a well defined cartilage tumor close to a non-cartilaginous, high grade sarcoma. This is usually thought of as a tumor where benign cartilage tumor or low grade chondrosarcoma converts into a high grade sarcoma with characteristics of fibrosarcoma, osteosarcoma or malignant fibrous histiocytoma. Radiological tests reveal ill defined, interosseous, lytic lesions along with cortical disruption and extension into the soft tissues. The prognosis is not good.
- Myxoid Chondrosarcoma: This is a slow-growing tumor with prominent myxoid degeneration. This has increased chances of metastasis and local recurrence.
Causes of Chondrosarcoma
Just as is the case with all the cancers, the exact cause of chondrosarcoma is also not clear. Certain medical conditions increase the risk for developing Chondrosarcoma and these are:
- Maffucci syndrome.
- Ollier disease.
- Hereditary Multiple Exostoses (osteochondromatoses).
- Paget’s disease.
- Wilms’ Tumor.
- Previous chemotherapy or radiation therapy for some other disease.
Symptoms of Chondrosarcoma
Patients suffering from chondrosarcoma commonly do not have symptoms or feel any sickness. A bony bump can be felt by the patient. Patient also can eventually feel pain, have swelling with restricted movement due to the tumor.
Difference between Benign & Malignant Cartilage Tumor
Chondrosarcoma is a malignant tumor or sarcoma of the connective tissue; whereas a chondroma is benign bone tumor, which is not a sarcoma. Benign bone tumors are not life threatening and do not metastasize to other organs and tissues. Benign bone tumors are usually left alone or are surgically removed if the patient is having symptoms, such as tenderness, pain, pressure from the benign tumor.
Malignant tumors, which originate from the skeletal system, occur rarely. Osteosarcoma is the most common type of bone cancer. It develops in new tissue which is present within the growing bones. Around 25% of malignant bone cancers are chondrosarcoma.
Diagnosis of Chondrosarcoma
Chondrosarcoma is usually found on an x-ray where the bone tumor can be seen. It is difficult to differentiate between chondrosarcoma and a benign bone tumor on an x-ray. Other tests, such as CT scan, bone scan, MRI and PET scan, should be done as they provide detailed information about the tumor. Biopsy of the tumor is a definitive method for diagnosing chondrosarcoma.
Treatment of Chondrosarcoma
Surgery is the first line of treatment where complete removal of the tumor with a wide margin of healthy tissue is done. The common treatment technique used is Limb Salvage Surgery. Amputation may be required for advanced or recurrent cancer.
Majority of the chondrosarcomas, excluding mesenchymal Chondrosarcoma, do not respond to radiation therapy or chemotherapy. For this reason, surgical management becomes crucial for treating chondrosarcoma. Rarely, if there is involvement of skull in chondrosarcomas, then proton radiation therapy can help.
Research is going on to determine the effectiveness of Intralesional Curettage Surgery, as this is a less invasive surgery and removes lesser tissue for low grade chondrosarcomas.
In some cases, chemotherapy or radiation therapy is considered for those patients who have metastatic, recurrent or dedifferentiated chondrosarcoma. However, these treatments haven’t been effective till now.
Prognosis for Chondrosarcoma
The prognosis for chondrosarcoma depends on the tumor grade and the amount of surgery done. Generally, the prognosis is very good for low grade tumors with a small percentage for recurrence and metastasis. The prognosis gets bad as the grade of the tumor increases. De-differentiated tumors have the worst prognosis as they have the highest risk of metastasis and recurrence, with a poor survival rate.