Basics
Description
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A benign tumor of cartilaginous origin with a predilection for the epiphysis in skeletally immature patients
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Generally found in the epiphyses of long bones.
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The humerus is most commonly affected, followed by the tibia and femur .
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Synonyms: Codman tumor; Epiphyseal chondromatous giant cell tumor
Epidemiology
A slight male predominance (2:1) is noted .
Incidence
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This tumor is rare.
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In the largest series, chondroblastoma accounted for 1% of all skeletal neoplasms.
Risk Factors
None known
Genetics
No known genetic component exists.
Etiology
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The pathogenesis is unknown.
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Most authors agree that the neoplastic cells arise from cartilage-forming matrix cells or chondroblasts.
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The tumor may be related to chondromyxoid fibroma.
Associated Conditions
Aneurysmal bone cyst
Diagnosis
Signs and Symptoms
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Patients usually complain of mild to moderate chronic pain, often months to years in duration.
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Stiffness and effusion of the adjacent joint also are common.
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Local swelling is uncommon.
Physical Exam
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The adjacent joint may have an effusion and decreased ROM.
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A soft-tissue mass is uncommon.
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Joint tenderness is unusual.
Tests
Lab
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Tests are not helpful.
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All blood tests are within normal limits, including the ESR.
Imaging
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Radiography:
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The radiographic appearance is that of a lytic lesion in the epiphysis with a thin sclerotic rim.
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The sclerotic rim indicates the benign nature of the lesion.
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It may expand or deform the bone.
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Occasionally, punctate calcifications may be seen.
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The patient’s history and plain radiographs usually are sufficient for making the diagnosis.
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MRI:
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May be used if history and radiography are not definitive
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The boundary of the lesion on MRI scans should be distinct.
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Pathological Findings
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The diagnosis requires the presence of chondroblasts on microscopic section.
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Chondroblasts are small, round or polygonal cells with round or oval nuclei.
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Cells are described as looking plump or like fried eggs.
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A lattice of calcification extends between the cells (chicken wire) .
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Interspersed giant cells are a common feature and may lead to confusion with giant cell tumor.
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Areas of aneurysmal bone cyst degeneration also may be present.
Differential Diagnosis
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Enchondroma
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Giant cell tumor
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Osteomyelitis
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Fibrous dysplasia
Treatment
General Measures
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Surgical excision is recommended to prevent progressive growth of the lesion with destruction of the epiphysis.
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Bone grafting is needed.
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Surgery is sometimes technically demanding because of the need to preserve or reconstruct the nearby joint surface.
Activity
No restrictions on activity are necessary because pathologic fracture is not a problem.
Special Therapy
Physical Therapy
Therapy may be used to regain ROM and strength after surgery.
Surgery
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Because the tumor is considered benign, local measures suffice.
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Surgery generally involves curettage and bone grafting.
Follow-up
Prognosis
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The recurrence rate with chondroblastoma alone is 20% at 3 years.
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If the tumor has an aneurysmal component, the risk of recurrence is higher .
Complications
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Recurrence
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Joint stiffness
Patient Monitoring
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Follow-up care is necessary because recurrence is common.
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Radiographs should be repeated every 6-12 months after excision for ~2 years.
Miscellaneous
Codes
ICD9-CM
213.4 Chondroblastoma
Patient Teaching
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Patients should be counseled that the lesion is benign and rarely metastasizes (<2%).
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However, if the tumor is not removed, local morbidity may occur because of progressive enlargement of the involved epiphysis and destruction of the joint.
FAQ
Q: Is chemotherapy or radiation therapy needed for chondroblastoma?
A: Chondroblastoma is a benign bone tumor so there is no need for chemotherapy or radiation therapy.
Q: Is there any risk of getting a viral disease or hepatitis after curettage and bone grafting for a chondroblastoma?
A: In general, no risk exists. The graft materials are very safe in that all the cells and nonbone proteins are removed. The exception is fresh-frozen grafts, which have the same risk of viral transmission as a blood transfusion (~1 in 500,000).