Diseases & Conditions
Chondrosarcoma is a malignant tumor composed of cartilage-producing cells. It is the second most common primary malignancy of bone, and one of the most difficult bone tumors to diagnose and treat. There are
Diseases & Conditions
Chondrosarcoma is a malignant tumor composed of cartilage-producing cells. It is the second most common primary malignancy of bone, and one of the most difficult bone tumors to diagnose and treat. There are several types of chondrosarcomas.
Chondrosarcomas can be subdivided in several ways: by histologic grade, whether they arise de novo (primary) or from benign lesions (secondary), by location within the bone (central or peripheral), or by syndrome.
Division of chondrosarcoma lesions by histologic grade carries the most prognostic significance. The grade of the tumor is extremely important in terms of overall and disease-free survival. There is a significant difference in 10-year survival rates between patients with low-grade lesions and patients with high-grade lesions.
Histologic grading of chondrosarcomas can pose a diagnostic challenge to both the musculoskeletal pathologist and the surgeon. The histologic spectrum ranges from a benign cartilage lesion (enchondroma) to the high-grade or dedifferentiated chondrosarcoma.
Malignant lesions are often divided into three histologic grades: low (grade 1), medium (grade 2), and high (grade 3). However, although most pathologists agree with this three-tiered grading system, there is some variation in the grouping of lesions. This is exemplified by the fact that there are different percentages of grade 1, 2 and 3 tumors among the large chondrosarcoma treatment centers.
One of the main diagnostic dilemmas with chondrosarcoma is differentiating between benign active and low-grade malignant lesions. Histologically, these lesions can look very similar; thus, clinical and radiographic data must be used to distinguish between them.
Cartilage lesions can often be identified on the basis of their radiographic appearance. Enchondromas (benign cartilage lesions) are typically located in the metaphyseal and diaphyseal portions of the long bones and the short tubular bones of the hand. They are described as containing dense, stippled, or popcorn calcifications. There is no periosteal reaction, cortical breakthrough, or associated extra-osseous mass.
Chondrosarcomas have a more aggressive radiographic appearance. The specific radiographic findings depend on the type and grade of the lesion. A primary central chondrosarcoma generally arises within the metaphyseal portion of the bone. Low-grade chondrosarcomas often show endosteal scalloping and a small degree of osteolysis. Intermediate and high-grade lesions demonstrate more aggressive radiographic features, such as osteolysis, medullary expansion, cortical thickening, cortical disruption, and the presence of a soft-tissue mass.
Rosenthal and associates summarized the radiographic and computed tomographic findings in low-grade and high-grade lesions. Low-grade features include dense, widespread, and uniformly distributed calcifications and, when present, an eccentric lobular growth of a soft-tissue mass. High-grade features include faint amorphous calcifications, large noncalcified areas, and concentric growth of a soft-tissue mass.
Additional imaging modalities are often helpful in the diagnosis and staging of malignant cartilage lesions. Computed tomography (CT) can evaluate the osseous architecture for endosteal scalloping, cortical thickening, or disruption. In addition, CT is helpful in identifying the pattern and extent of calcifications.
Magnetic resonance imaging (MRI) is useful in determining the intraosseous extent of the lesion, particularly the nonmineralized portion of the lesion. It has been proposed that the percentage of medullary cavity that is occupied by the lesion is predictive of malignancy. Medullary fill greater than 90% is associated with the diagnosis of chondrosarcoma. MRI will also define the soft-tissue mass and its relationship to the surrounding anatomy, such as the neurovascular bundle, the joint, and the joint capsule.
All cartilage lesions, both benign and malignant, tend to be "hot" on whole-body technetium-99m diphosphonate bone scans. However, it has been postulated that chondrosarcomas, unlike enchondromas, tend to have greater uptake within the lesion compared with an internal standard such as the anterior superior iliac spine.
The clinical presentation of cartilage lesions varies depending on the location and type of the lesion.
Benign cartilage lesions, enchondromas, of the long bones are usually asymptomatic and are most often incide