General Considerations

• Rare, benign bone tumor that arises in the epiphysis of long bones in skeletally immature patients
• Usually occurs under the age of 20; males greater than females
• Most common locations are in lower extremity (70%)
  • 50% occur around knee
• Femur most common
• Most chondroblastomas of the proximal femur occur in the greater trochanter
• Proximal tibia
• Proximal humerus
• Most occur in humeral head
• About 10% occur in the small bones of the hands and feet
• May also occur in apophyses
• Most common tumor of patella

Clinical Findings

• Pain
• Limitation of motion
• Redness
• Swelling

Imaging Findings

• Conventional radiographs are usually diagnostic
• Geographic lytic lesion arising in the epiphysis of a child
• May have scalloping or expansion of epiphyseal cortex
• May extend to adjacent metaphysis
• Eccentric
• Up to half may have internal calcifications
• Well-defined sclerotic margin
• CT or MRI are used to evaluate
  • Extent of involvement of epiphysis
• Proximity of lesion to articular cartilage
• On MRI
• Low signal intensity on T1
• High or variable intensity on T2

Differential Diagnosis

• Counterpart of chondroblastoma in a child is giant cell tumor (GCT) of an adult
  • GCT arise later in life (20-30)
• Frequently extend to metaphysis

Treatment

• Curettage
• Packing with allograft or autograft bone chips or methylmethacrylate

Complications

• High rate of recurrence (up to 1/3)
  • Most common locations for recurrence to occur are proximal femur and pelvis
• Pathologic fractures
  • Very rare
• Malignant transformation
  • Extremely rare
• Pulmonary metastases or local invasion are possible, even with “benign” tumors

Prognosis

• Excellent

 

 

 

Chondroblastoma. A geographic, lytic lesion is seen in the epiphysis (white and blue arrows)
of a skeletally immature (red arrow) male's distal femur. The lesion has a sclerotic margin and is septated.
It is confined to the epiphysis. The findings are characteristic of a chondroblastoma, a rare benign bone tumor.
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Wheeless Textbook of Orthopedics

eMedicine  Chondroblastoma: Fines, B and Stacy, G