Chondrosarcoma is the third most common malignant bone tumor behind myeloma and osteosarcoma. Although rare in presentation, an estimated 600 patients receive this diagnosis each year in the United States.
Chondrosarcomas typically occur in flat bones, including the shoulder and pelvic girdles, but may also occur in the extremities. Common presentation includes males between the ages of 40 years and 60 years with deep pain that is persistent at rest.
Chondrosarcomas can appear on radiographic imaging as a low-grade intracompartmental lesion, such as an enchondroma. However, serial radiographs done each month will show continued growth with chondrosarcomas.
Chondrosarcomas come in two forms: Primary and secondary. Primary chondrosarcomas arise de novo from the intramedullary space of bone. Secondary chondrosarcomas arise from preexisting benign lesions, such as osteochondromas, multiple hereditary exostosis, enchondromas, Ollier’s disease, and Maffucci’s syndrome. Typically, 85% of chondrosarcomas are classified as grade 1 or 2.
On standard x-ray, it can be difficult to differentiate between benign lesions and chondrosarcomas. X-rays will likely show a lytic, lobular lesion with a pattern of calcification within a cartilaginous matrix. Low-grade lesions may show cortical thickening and endosteal erosion, whereas high-grade lesions show cortical destruction and soft tissue invasion.
Computed tomography (CT) is sensitive in determining the extent of cortical destruction and the presence of new lucencies, which suggest malignant transformation. CT scan of the chest may be performed, as high-grade tumors are prone to pulmonary metastases. MRI may be used to determine the extent of soft tissue involvement.
Generally, chondrosarcoma is a slow-growing malignancy, but the aggressiveness of the tumor can vary. Radiographic appearance and histologic findings are not great predictors of tumor aggression. Factors that suggest a high-grade malignancy include increasing size of the tumor, the presence of pain that persists at rest, and age greater than 40 years. Lesions located in the pelvis and proximal extremities are more likely to be malignant than tumors in the distal extremities.
The diagnosis is often influenced by clinical history and physical exam findings, since radiographic and histologic findings are unreliable in confirming the diagnosis. Pain, inflammation, and increasing tumor size suggest malignancy. Serial radiographs that monitor changes in tumor size over time may be the most accurate method in determining malignant potential.
A definitive diagnosis is established by correlating clinical and radiographic findings, gross pathologic findings, and histopathologic findings. A biopsy may be performed before a definitive surgical procedure. However, biopsy results poorly differentiate between low-grade and high-grade lesions and therefore, are not usually helpful in preoperative planning. Special care should be taken during biopsy to avoid spreading tumor cells along the needle tract.
Treatment is often dictated by the tumor grade, which is based on histologic findings, anatomic location, and the presence or absence of metastasis. Radiation and chemotherapy treatments are ineffective due to the slow-growing nature and poor vascularity of chondrosarcomas. Surgical intervention, including intralesional curettage or wide surgical excision, is the treatment of choice for all chondrosarcomas. However, intralesional curettage is primarily used in low-grade lesions in the extremities but is not recommended for chondrosarcomas of the pelvis due to the higher recurrence rates.
Wide surgical excision involves resection of the bone involved and surrounding tissue with the goal of removing all malignant cells. During a wide surgical excision, intraoperative tissue is sent for frozen section until all margins are free of malignant cells. If tumor cells are noted on the marginal excision tissue, then the margins are widened during the same operative setting until all margins are negative.
Dagan Cloutier, MPAS, PA-C, practices in a multispeciality orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopedics for Physician Assistants (JOPA).
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