Chondroblastoma

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Rohan A. Bhimani, M.B.B.S., D.N.B., M.Ch.[2]

Synonyms and keywords: Codman tumor; Codman's tumor; Codman tumour; Codmans tumor; Chondroblastomas; Benign chondroblastoma; Epiphyseal chondroblastoma

Overview

Chondroblastoma is a benign cartilaginous tumor that account for 1% of all bone tumors. Chondroblastoma typically occurs in children and adolescents between 10 and 25 years of age. Male are more commonly affected with chondroblastoma than female. The male to female ratio is approximately 2:1. The epiphysis of the distal femur, proximal tibia, and proximal humerus are the most common sites. In 1928, Codman first described chondroblastoma as epiphyseal chondromatous giant cell tumors of the proximal humerus. The exact pathogenesis of chondroblaroma is not fully understood. Various theories have been postulated such as chondroblastoma arising from osteoid matrix–containing type I collagen and there is absence of true cartilage matrix production (Type II collagen). Recently a specific mutation in the histone 3 gene H3F3B (K36M), was identified in approximately 95% of chondroblastomas. The hallmark of chondroblastoma is pain, limping, tenderness to palpation and restricted range of motion. If left untreated, few patients with chondroblastoma may progress to develop lung metastasis. The mainstay of treatment for chondroblastoma is surgery in form of curettage and bone grafting.

Historical Perspective

• In 1928, Codman first described chondroblastoma as epiphyseal chondromatous giant cell tumors of the proximal humerus.
• In 1942, Jaffe and Lichenstein later recognized it as a distinct entity due to its chondorid matrix.

Classification

Chondroblastoma can be classified based on imaging findings.

Enneking (MSTS) Staging System

• The Enneking surgical staging system (also known as the MSTS system) for benign musculoskeletal tumors based on radiographic characteristics of the tumor host margin.
• It is widely accepted and routinely used classification.

Stages	Description
1	Latent: Well demarcated borders
2	Active: Indistinct borders
3	Aggressive: Indistinct borders

Pathophysiology

• The exact pathogenesis of chondroblaroma is not fully understood.
• Various theories have been proposed concerning the pathogenesis of chondroblastomas:
  • Chondroblastoma tumors are of chondrogenic origin.
  • Chondroblastoma arises from osteoid matrix–containing type I collagen and the absence of true cartilage matrix production (Type II collagen).
  • chondroblastoma arises from an intraosseous proliferation of tendon sheath cells that have a predilection for chondroid formation.
• Chondroblastomas typically occur in the epiphyses and apophysis of the long bones.
• The bones often involved by epiphyseal chondroblastomas are femur, tibia, and humerus.

Genetics

• Chondroblastoma may have association with genetic abnormalities on chromosome 5 and 8.
• Recently a specific mutation in the histone 3 gene H3F3B (K36M), was identified in approximately 95% of chondroblastomas.

Causes

There are no established causes for chondroblastoma.

Differentiating Chondroblastoma from Other Diseases

• Chondroblastoma must be differentiated from following bone disorders:

Disease	Epiphyseal lesion	Benign lesion that may metastasize to lung	Diagnosis	Treatment is curretage and bone grafting
Chondroblastoma	+	+	Radiology and biopsy	+
Giant Cell Tumor	+	+	Radiology and biopsy	+
Aneurysmal bone cyst	-	-	Radiology and biopsy	+
Osteoblastoma	-	-	Biopsy	+
Chondromyxoid Fibroma	-	-	Radiology and biopsy	+

Epidemiology and Demographics

• Chondroblastoma is a rare benign bone tumor accounting for approximately 1% of all benign bone tumors.
• Adolescents and children are most affected by chondroblastoma.
• The age distribution of chondroblastoma is between 10-25 years.
• The mean age of the patients with osteoid osteoma is 22 years.
• Men are more commonly affected than women, with a 2:1 ratio.
• There is no racial predilection to chondroblastoma.

Risk Factors

There are no established risk factors for chondroblastoma.

Screening

There is insufficient evidence to recommend routine screening for chondroblastoma.

Natural History, Complications, and Prognosis

• If left untreated, few patients with chondroblastoma may progress to develop lung metastasis.
• Common complications of chondroblastoma include:
  • Pathological fracture
  • Premature epiphyseal closure
    • Limb-length discrepancy
    • Angular deformity
  • Malignant transformation
  • Metastasis to other organs
    • Metastasis most frequently involves the lungs and tends to occur at the time of primary tumor recurrence
    • Other sites of metastasis are secondary bone sites, soft tissue, skin, or the liver
• Depending on the extent of the tumor at the time of diagnosis, the prognosis may vary. However, the prognosis is generally regarded as excellent.
• Factors that influence the outcome of the chondroblastoma include:
  • Extent of the tumor
  • Size and location of the tumor
  • Pulmonary metastasis
  • Tumor response to the therapy

Diagnosis

Diagnostic Study of Choice

• X-ray is the diagnostic study of choice for the diagnosis of chondroblastoma.
• X-ray findings include:
• Well-circumscribed eccentric oval or round lytic lesion that usually involves the adjacent bone cortex without periosteal reaction
• A sclerotic margin can be observed in some cases
• For long bone chondroblastoma the tumor is typically contained to the epiphysis or apophysis but may extend through the epiphyseal plate
• A mottled appearance on the radiograph indicates areas of calcification which is commonly associated with skeletally immature patients
• In cases involving older patients or flat bones, typical radiographic presentation is not as common and may mimic aggressive processes

History and Symptoms

Symptoms of chondroblastoma include:

• Localized bone pain with activity and rest
  • Pain often present for months or years; frequently misdiagnosed as chronic synovitis
• Localized swelling
• Decreased range of motion of the affected joint
• Limp

Physical Examination

• Patients with chondroblastoma usually appears well.
• Common physical examination findings of chondroblastoma include:
  • Tenderness to palpation

X-ray of Knee: Chondroblastoma of proximal tibia.Source: Case courtesy of Radswiki, Radiopaedia.org, rID: 11302

• • Soft tissue swelling
  • Decreased range of motion
  • Muscle atrophy
  • Joint effusion

Laboratory Findings

There are no diagnostic laboratory findings associated with chondroblastoma.

Electrocardiogram

There are no ECG findings associated with chondroblastoma.

X-ray

• Three views of affected bone or joint are recommended.
• X-ray findings include:
  • well-circumscribed epiphyseal lytic lesion with thin rim of sclerotic bone that is sharply demarcated from normal medullary cavity .
  • Lesions often cross physis into metaphysis.
  • Stippled calcifications within the lesion may or may not be present (25%-45%).
  • Cortical expansion may be present.
  • Soft tissue expansion rare.

CT scan of Knee: Chondroblastoma is subchondral, lytic, having geographic appearance, narrow transitional zone and surrounding sclerosis..Source:Case courtesy of Dr Ali Abougazia, Radiopaedia.org, rID: 25725

Chest X-Ray

• Chest radiograph should be done to look for benign pulmonary metastases which may occasionally may occur with chondroblastoma.

Echocardiography or Ultrasound

There are no echocardiography/ultrasound findings associated with chondroblastoma.

CT scan

CT findings for chondroblastoma include:

• Lacelike matrix mineralization along with scalloped borders.
• Periosteal reaction.
• It also defines bony extent of the lesion.

MRI

• MRI of chondroblastoma is ideal for the evaluation of transphyseal or transcortical extension, and for demonstrating associated surrounding bone marrow and soft tissue edema, which is observed in a large proportion of cases.
• MRI Findings include:

MRI scan of Knee: High T2 signals with a thin sclerotic rim and surrounding marrow edema..Source:Case courtesy of Dr Ali Abougazia, Radiopaedia.org, rID: 25725

• • The lesions have signal typical of cartilage:
    • T1: low to intermediate signal
    • T2: intermediate to high signal
  • Focal lobules of low, intermediate, and high signal intensity most likely correspond to calcification, chondroid matrix, and fluid in the lesion.
  • MRI may also reveal an effusion of the joint.
  • Fluid-fluid levels may occasionally be observed presumably due to an associated aneurysmal bone cyst.

Other Imaging Findings

There are no other imaging findings associated with chondroblastoma.

Biopsy

• Biopsy may be helpful in the diagnosis of chondroblastoma.
• Biopsy grossly demonstrates the following features:
  • Irregularly lobulated, hemorrhagic, bluish gray, and gritty lesions that expands the epiphysis.

Histological appearance: Chondroblastoma

• On histological examination:
  • Chondroblasts arranged in "cobblestone" or "chickenwire" pattern may be present.
  • Scattered multinucleated giant cells with focal areas of chondroid matrix.
  • Occasional multinucleated giant cells may be present
  • Mononuclear stromal cells are distinct, S100+ cells with large central nuclei.
    • Nuclei have longitudinal groove resembling coffee bean.
  • One-third of chonroblastomas have areas of secondary Aneurysmal bone cyst.

Treatment

Medical Therapy

There is no treatment for chondroblastoma; the mainstay of therapy is surgery.

Surgery

Surgery is the mainstay of treatment for chondroblastoma.

Extended Intralesional Curettage and Bone Grafting

Indications

• Symptomatic individuals

Technique

• Local adjuvant treatment with phenol or cryotherapy to decrease local recurrence

Radiofrequency Ablation

• Another procedure that may be used for the management of chondroblastoma is radiofrequency ablation which is less invasive and has less recovery time.
• Radiofrequency ablation is typically most successful for small chondroblastoma lesions about 1.5 cm.

Surgical Resection

Indications

• Pulmonary metastasis

Recurrence

• Local recurrence rate is 10-15% after treatment.

Primary Prevention

There are no established measures for the primary prevention of chondroblastoma.

Secondary Prevention

There are no established measures for the secondary prevention of chondroblastoma.

References

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