Introduction
Background
A chondroblastoma is a rare benign cartilaginous neoplasm that characteristically arises in the epiphysis of a long bone in young patients.1,2 (Also see the eMedicine Orthopedic Surgery article Chondroblastoma.)
Pathophysiology
Chondroblastomas consist of chondroblasts, which are round or oval primitive cells of the epiphyseal cartilage plate that contain dense eosinophilic cytoplasm. Cellular areas are surrounded by variable amounts of dense eosinophilic matrix and may contain coarse calcifications or calcifications in a chicken-wire pattern. Mitotic figures and cytologic atypia are rare. Cystic changes may simulate those of aneurysmal bone cysts (see Image 22), especially when the tumor occurs in the patella, talus, or calcaneus.3
Frequency
United States
Chondroblastomas represent less than 1% of all primary bone tumors.1,2 These lesions are less common than enchondromas and osteochondromas but more common than chondromyxoid fibromas.
International
The worldwide data for chondroblastomas are the same as those in the United States.
Mortality/Morbidity
Complications associated with chondroblastomas include pathologic fractures (see Images 18-19) and, rarely, malignant transformation. Fractures are uncommon and proportionally more likely to occur in tumors of increasing size. Without surgical excision, the tumor may extend into the adjacent soft tissues or synovium and metastasize to distant organs. Metastasis, when it occurs, most frequently involves the lungs and tends to occur at the time of primary tumor recurrence.4,5 Widespread metastases and death have been reported.4,5,6
Sex
There is a male preponderance for chondroblastomas. The male-to-female ratio is 2-3:1.
Age
Chondroblastomas generally occur in those aged 10-30 years; in the literature, the age range of affected patients has been 3-73 years for tumor occurrence. About 90% of the tumors occur in those aged 5-25 years.
Anatomy
Chondroblastomas typically occur in the epiphysis or apophysis of a long tubular bone, and the tumor is confined to the epiphysis in 40% of cases. In the remainder of the cases, the tumor extends to the adjacent metaphysis. Rarely, chondroblastomas arise in the metaphysis and, even less frequently, in the diaphysis.
The most commonly affected site is the lower extremity (72% of cases), in which 50% of the chondroblastomas occur around the knee (see Images 1 and 5). The femur is involved in 33% of cases; the humerus, in 20%; and the tibia, in 18%. Lesions in the proximal femur are 3 times more likely to occur in the greater trochanter than in the femoral head (see Image 8). About 90% of the lesions in the humerus occur in the proximal humeral head (see Image 10).
Approximately 10% of all chondroblastomas occur in the small bones of the hands and feet; the talus and calcaneus are common sites (see Image 13). Other rare sites include the para-acetabular innominate bone, ribs, skull, mandible, maxillae, vertebrae, scapulae, patellae, and sternum (see Images 14, 18, and 20). Case reports describe occurrences in the temporal bone7 and thoracic spine.8
Presentation
The symptoms and signs of chondroblastomas are nonspecific and include local pain, tenderness, swelling, and muscle wasting. Joint effusion occurs in approximately 30% of patients. Symptoms may vary in duration (months to years) before diagnosis.
A relatively high rate of tumor recurrence (10-35%) has been reported for chondroblastomas.6 Risk factors for recurrence include a larger-than-average lesion (>3.7 cm), a secondary aneurysmal bone cyst, and a location in the proximal femur or pelvis.6 The recurrence with the last factor may be due to the difficulty in gaining surgical access in these locations and to cautiousness in removing the lesion to avoid compromising the blood supply to the femoral head.
Preferred Examination
The preferred modalities for evaluation of chondroblastomas are standard radiography and either computed tomography (CT) scanning or magnetic resonance imaging (MRI).
Limitations of Techniques
Underexposed radiographs may fail to depict a chondroblastoma. CT scanning may be useful for the better definition of possible cortical erosion and matrix mineralization, although this modality is usually inferior to MRI in the evaluation of transphyseal or transcortical extension, both of which are important factors in preoperative planning. Other modalities may be useful on a case-by-case basis.
Differential Diagnoses
Chondrosarcoma
Eosinophilic Granuloma, Skeletal
Giant Cell Tumor
Hemangioma, Bone
Osteomyelitis
Other Problems to Be Considered
Degenerative cysts of osteoarthritis (eg, subchondral cysts, geodes)
Intraosseous ganglion
Avascular necrosis
More on Chondroblastoma |
 Overview: Chondroblastoma |
| Imaging: Chondroblastoma |
| Follow-up: Chondroblastoma |
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References
Resnik D. Tumors and tumor-like lesions of bone: imaging and pathology of specific lesions. Diagnosis of Bone and Joint Disorders. 3rd ed. Philadelphia, Co: WB Saunders Co; 1995:3711-20.
Brower AC, Moser RP, Gilkey FW. Chondroblastoma. In: Davidson AJ, ed. Cartilaginous Tumors of the Skeleton Skeleton: AFIP Atlas of Radiologic-Pathologic Correlations Fascicle II. Philadelphia, Pa: Hanley & Belfus; 1990:74-113.
Ghekiere J, Geusens E, Lateur L, et al. Chondroblastoma of the patella with a secondary aneurysmal bone cyst. Eur Radiol. 1998;8(6):992-5. [Medline].
Jambhekar NA, Desai PB, Chitale DA, Patil P, Arya S. Benign metastasizing chondroblastoma: a case report. Cancer. Feb 15 1998;82(4):675-8. [Medline]. [Full Text].
Khalili K, White LM, Kandel RA, Wunder JS. Chondroblastoma with multiple distant soft tissue metastases. Skeletal Radiol. Aug 1997;26(8):493-6. [Medline].
Ramappa AJ, Lee FY, Tang P, et al. Chondroblastoma of bone. J Bone Joint Surg Am. Aug 2000;82-A(8):1140-5. [Medline].
Shek TW. Chondroblastoma of temporal bone. Am J Otol. Jul 2000;21(4):597-8. [Medline].
Attar A, Ugur HC, Caglar YS, Erdogan A, Ozdemir N. Chondroblastoma of the thoracic vertebra. J Clin Neurosci. Jan 2001;8(1):59-60. [Medline].
Jee WH, Park YK, McCauley TR, et al. Chondroblastoma: MR characteristics with pathologic correlation. J Comput Assist Tomogr. Sep-Oct 1999;23(5):721-6. [Medline].
Aigner T, Loos S, Inwards C, et al. Chondroblastoma is an osteoid-forming, but not cartilage-forming neoplasm. J Pathol. Dec 1999;189(4):463-9. [Medline].
Atalar H, Basarir K, Yildiz Y, Erekul S, Saglik Y. Management of chondroblastoma: retrospective review of 28 patients. J Orthop Sci. Jul 2007;12(4):334-40. [Medline].
Brien EW, Mirra JM, Kerr R. 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. Jun 1997;26(6):325-53. [Medline].
Keenan S, Bui-Mansfield LT. Musculoskeletal lesions with fluid-fluid level: a pictorial essay. J Comput Assist Tomogr. May-Jun 2006;30(3):517-24. [Medline].
Tins B, Cassar-Pullicino V, McCall I, et al. Radiofrequency ablation of chondroblastoma using a multi-tined expandable electrode system: initial results. Eur Radiol. Apr 2006;16(4):804-10. [Medline].
Van Dyck P, Vanhoenacker FM, Vogel J, et al. Prevalence, extension and characteristics of fluid-fluid levels in bone and soft tissue tumors. Eur Radiol. Dec 2006;16(12):2644-51. [Medline].
Further Reading
Keywords
Codman tumor, cartilage-containing giant cell tumor, calcified giant cell tumor, epiphyseal chondromatous giant cell tumor, epiphyseal tumors, benign cartilaginous neoplasms, chondroclasts
