Search

Chondrosarcoma is a malignant tumor of cartilage-producing cells35. It is subdivided in a variety of ways, including by histological grade, by whether it is primary or secondary, and by whether it is peripheral or central; among these, the single most prognostic sub-classification is the histological grade. In addition, there are a few specific histological subtypes of chondrosarcoma: clear-cell, mesenchymal, base of the skull, and soft-parts chondrosarcoma. Chondrosarcoma is most often separated into three histological grades: low (grade 1), medium (grade 2), and high (grade 3). The higher the grade, the more likely it is that the tumor will metastasize. Grading is based on the tumor's histological appearance, with tumors that most resemble normal cartilage being low-grade (grade 1) and having the least risk of metastasizing, and those that have the most abnormal-appearing cartilage being high-grade (grade 3) and having a higher risk of metastasizing (Figs. 1 and 2). A type of chondrosarcoma that has a higher risk of metastasizing than a grade-3 chondrosarcoma is the uncommon, so-called dedifferentiated chondrosarcoma7,24. This chondrosarcoma is believed to arise from a benign cartilage lesion or a low-grade chondrosarcoma. On histological examination, it has areas of malignant spindle cells that cannot be recognized as being of cartilaginous origin, adjacent to areas of neoplastic chondrocytes surrounded by a hyaline-cartilage matrix. The dedifferentiated chondrosarcoma is the most malignant of the chondrosarcomas and has an extremely high risk of distant metastasis. A review of the experience at the Mayo Clinic with dedifferentiated chondrosarcoma found that only eight of seventy-eight patients who had such a lesion survived for more than five years after the initial diagnosis12. This finding is consistent with the four and five-year survival rates reported in other studies3,8. Photomicrograph of a low-grade chondrosarcoma. The …

We studied 217 consecutive tumors of bone by flow cytometric analysis of nuclear DNA concentration after staining with propidium iodide. A diagnosis and histological grade (benign, low-grade, or high-grade sarcoma) were assigned to each tumor on the basis of staging data (with the exception of the forty-six giant-cell tumors, which, although indistinguishable histologically, were divided according to the flow cytometric pattern into two distinct groups), and we quantitatively studied the flow cytometry data to assess the percentages of cells in diploidy, tetraploidy, or aneuploidy. When compared, the mean values for the flow cytometric data for the three grades showed significant differences. Criteria were established for the three classes of tumors: for benign tumors, less than 11 per cent tetraploidy and no aneuploidy; for low-grade sarcomas, more than 11 per cent and less than 17 per cent tetraploidy, and no aneuploidy; and for high-grade tumors, either more than 17 per cent tetraploidy or aneuploidy. Tests for compliance for all groups of tumors (excluding the forty-six giant-cell tumors)--benign, low grade, or high grade--were significant for most of the benign lesions (with the exception of chondroblastoma and fibrous dysplasia) and for the high-grade sarcomas (with the exception of round-cell tumors). The low-grade sarcomas did far less well, based principally on the failure of the low-grade chondrosarcomas, chordomas, and adamantinomas to comply with the criteria. An attempt to assess the value of the system as a predictor of metastases showed that a low percentage of diploid cells (less than 75 per cent) and the presence of an aneuploid peak correlated statistically with the development of metastatic disease, but the usefulness of this observation could not be fully assessed because of multiple variables, associated principally with treatment.

In defining the linear extent of a malignant tumor in a long bone, radiographs, computerized tomography, and scintigraphy are routinely employed, especially when non-ablative surgery is being considered. The drawbacks of these modalities in defining the true intracompartmental extent of disease within a bone can largely be overcome with the use of magnetic resonance imaging. We did a prospective analysis of magnetic resonance imaging in sixteen consecutive patients with a primary malignant tumor of a long bone, and it showed that this modality has clinical promise of being more precise than the other modalities in defining the true proximal and distal extent of a tumor in a long bone. Coronal images permit easier planning of surgical techniques for salvage of a limb using an allograft than do a multiplicity of transverse images.