This study supports application of a standardized measuring technique for improved distinction of benign osteochondromas from chondrosarcomas, with a cartilage cap thickness of 2 cm or greater as the determinant of chondrosarcoma.
To validate a technique for reproducible measurement of the osteochondroma cartilage cap with computed tomography (CT) and magnetic resonance (MR) imaging and to reevaluate the correlation of the thickness of the cartilage cap with pathologic findings to improve noninvasive differentiation of benign osteochondromas from secondary chondrosarcomas.
Materials and Methods
The institutional review board approved the study and waived the need for informed consent. HIPAA compliance was maintained. After validation of the measurement technique, 101 pathologically confirmed osteochondromas were retrospectively reviewed. Patient demographic data, histologic diagnosis, and chondrosarcoma grade were recorded. Two musculoskeletal radiologists used a standardized technique to independently measure the thicknesses of the cartilage caps on CT and MR images; these measurements were compared for interobserver agreement. Agreement between measurements with CT and MR imaging was also evaluated, as were the sensitivity and specificity of both modalities for differentiation of osteochondromas from chondrosarcomas.
Evaluated were 67 benign osteochondromas (from 49 male patients and 18 female patients; mean age, 23.4 years) and 34 secondary chondrosarcomas (from 27 male patients and seven female patients; mean age, 33.2 years). On the basis of the proposed measuring technique, there was 88% interobserver measurement agreement with MR imaging (95% confidence interval [CI]: 80%, 94%) and 93% with CT (95% CI: 84%, 98%). The median difference between measurements of cap thickness at CT and MR imaging was 0 cm (25th and 75th percentiles, –3 mm and 1 mm, respectively). With 2 cm used as a cutoff for distinguishing benign osteochondromas from chondrosarcomas, the sensitivities and specificities were 100% and 98% for MR imaging and 100% and 95% for CT, respectively.
The proposed measuring technique allows accurate and reproducible measurement of cartilage cap thickness with both CT and MR imaging. Cap thickness of 2 cm or greater strongly indicated secondary chondrosarcomas.
© RSNA, 2010
- 1 . Imaging of osteochondroma: variants and complications with radiologic-pathologic correlation. RadioGraphics 2000;20(5):1407–1434. Link, Google Scholar
- 2 . Hereditary multiple exostoses: report of a kindred. J Med Genet 1981;18(6):428–430. Crossref, Medline, Google Scholar
Skeletal Lesions Interobserver Correlation among Expert Diagnosticians (SLICED) Study Group. Reliability of histopathologic and radiologic grading of cartilaginous neoplasms in long bones. J Bone Joint Surg Am 2007;89(10):2113–2123. Crossref, Medline, Google Scholar
- 4 . Chondrosarcoma of bone. Am J Pathol 1943;19(4):553–589. Medline, Google Scholar
- 5 . Tumors of bone and cartilage. In: Spjut HJDorfman HDFechner FEAckerman LV, eds. Atlas of tumor pathology. 2nd series, fascicle 5. Washington, DC: Armed Forces Institute of Pathology, 1971; 84–110. Google Scholar
- 6 . Bone and soft-tissue tumors. In: Stoller DW, ed. Magnetic resonance imaging in orthopaedics and sports medicine. 3rd ed. Philadelphia, Pa: Lippincott Williams & Wilkins, 2006; 2065–2070. Google Scholar
- 7 . Secondary chondrosarcoma in osteochondroma: report of 107 patients. Clin Orthop Relat Res 2003;411(411):193–206. Crossref, Medline, Google Scholar
- 8 . Chondrosarcoma arising in osteochondroma. Cancer 1982;49(9):1890–1897. Crossref, Medline, Google Scholar
- 9 . Cartilaginous tumors: correlation of gadolinium-enhanced MR imaging and histopathologic findings. Radiology 1993;186(3):813–817. Link, Google Scholar
- 10 . Benign exostoses and exostotic chondrosarcomas: evaluation of cartilage thickness by CT. Radiology 1984;152(3):595–599. Link, Google Scholar
- 11 . The use of computed tomography to distinguish osteochondroma and chondrosarcoma. Radiology 1981;139(1):129–137. Link, Google Scholar
- 12 . Radiographic hallmarks of peripheral chondrosarcoma. Radiology 1984;151(3):589–596. Link, Google Scholar
- 13 . Hyaline cartilage-origin bone and soft-tissue neoplasms: MR appearance and histologic correlation. Radiology 1988;167(2):477–481. Link, Google Scholar
- 14 . MR imaging of solitary osteochondromas: report of eight cases. AJR Am J Roentgenol 1987;149(3):557–560. Crossref, Medline, Google Scholar
- 15 . Benign and malignant cartilage tumors of bone and joint: their anatomic and theoretical basis with an emphasis on radiology, pathology and clinical biology. II. Juxtacortical cartilage tumors. Skeletal Radiol 1999;28(1):1–20. Crossref, Medline, Google Scholar
- 16 . Prognostic factors in chondrosarcoma of bone: a clinicopathologic analysis with emphasis on histologic grading. Cancer 1977;40(2):818–831. Crossref, Medline, Google Scholar
- 17 . Imaging hyaline cartilage. Br J Radiol 2003;76(911):777–787. Crossref, Medline, Google Scholar
- 18 . Benign and malignant cartilage tumors of bone and joint: their anatomic and theoretical basis with an emphasis on radiology, pathology and clinical biology. I. The intramedullary cartilage tumors. Skeletal Radiol 1997;26(6):325–353. Crossref, Medline, Google Scholar
- 19 . Osteochondroma (osteocartilaginous exostosis). In: Unni KK, ed. Dahlin’s bone tumors: general aspects and data on 11,087 cases. 5th ed. Philadelphia, Pa:Lippincott-Raven, 1996; 11–23. Google Scholar
- 20 . Bursitis in association with solitary osteochondromas presenting as mass lesions. Skeletal Radiol 1991;20(7):513–516. Crossref, Medline, Google Scholar
- 21 . Symptomatic osteochondromas: imaging features. AJR Am J Roentgenol 1997;168(6):1507–1512. Crossref, Medline, Google Scholar
- 22 . Symptomatic bursa formation with osteochondromas. AJR Am J Roentgenol 1979;133(5):895–898. Crossref, Medline, Google Scholar
- 23 . Scapular osteochondroma presenting with exostosis bursata. Bull Hosp Jt Dis 1993;52(2):55–58. Medline, Google Scholar
- 24 . Large bursa formation associated with osteochondroma of the scapula: a case report and review of the literature. Jpn J Clin Oncol 1999;29(7):356–360. Crossref, Medline, Google Scholar
- 25 . Case report 143. Multiple hereditary osteocartilaginous exostoses affecting right femur with an overlying giant cystic bursa (exostosis bursata). Skeletal Radiol 1981;6(2):134–137. Crossref, Medline, Google Scholar
- 26 . Fat-suppressed three-dimensional spoiled gradient-recalled MR imaging: assessment of articular and physeal hyaline cartilage. AJR Am J Roentgenol 1997;169(4):1117–1123. Crossref, Medline, Google Scholar
- 27 . Malignant transformation of a multiple cartilaginous exostosis: a case report. Int Orthop 1997;21(2):133–136. Crossref, Medline, Google Scholar
Article HistoryReceived November 28, 2008; revision requested January 19, 2009; revision received October 12; accepted October 21; final version accepted November 16.
Published online: June 2010
Published in print: June 2010