Bone Tumors
Chondroblastoma
James C. Wittig, MD
Sarcoma Surgeon
Orthopedic Oncologist
GENERAL INFORMATION
Benign neoplasm of immature cartilage cell (chondroblast) proliferation
Cells resemble chondrocytes/chondroblasts
Marked predilection for arising from the epiphysis
Usually occurs in skeletally immature patients
<1% of osseous neoplasms
High propensity for local recurrence
Codman Tumor (old historical name for chondroblastoma)
Cartilage Containing Giant Cell Tumor
Kolodney 1972
Calcifying Giant Cell Tumor
Ewing 1928
Clinical Data
Rare; 1-2% all bone tumors
Male predilection (2:1)
Children and young adults; 90% 5-25 yrs. old
Benign Aggressive Tumor with High Propensity for Local Recurrence
Very rare cases that metastasize to the lungs
Location:
Almost all cases arise from the epiphysis of the bone
Epiphysis only 40% of cases
Epiphysis and metaphysis 55% of cases
Metaphysis only 4%
Epiphyseal Lesions
Differential Diagnosis of Lesions that tend to involve the epiphysis:
Chondroblastoma
Clear cell chondrosarcoma
Giant Cell Tumor (GCT)
Subchondral Cyst/Intraosseous Ganglion
Infection
Eosinophilic Granuloma (LCH)
Osteoid Osteoma
Osteoblastoma
Mets, myeloma, lymphoma
CLINICAL PRESENTATION
Signs/Symptoms: Mild Pain lasting from months to several years
33% of patients have a joint effusion and swelling with limitations in range of motion
Often confused with a sports injury
Sex Predilection: Male > Female 1.4:1
Age: Range 3 – 72 years
95% of cases occur between the ages 5 and 25
Most cases occur in adolescents between 10 and 20 years of age
Sites: Predilection for distal femur, proximal tibia & humerus
98% located in epiphysis, 30% in knee area
May also occur in calcaneus, talus and temporal bone
Most Common Sites:
Proximal Femur 23%
Distal Femur 20%
Head and Neck 16%
Trochanter 7%
Proximal Tibia 17%
Proximal Humerus 17%
Hands and Feet 10%
RADIOGRAPHIC PRESENTATION
Presents as a highly defined/well circumscribed geographic oval/round lytic defect
Surrounded by rim of sclerotic bone
Usually in epiphyseal region
Lesion ranges from 3 cm to 6 cm diameter
Usually radiolucent
May have fine trabeculae and irregular calcifications
Calcifications are often better detected with a CT scan but are not uniformly present
Lesions may expand the bone and new periosteal bone may form
Bony end plate, cortex, bone contour are unaffected
Plain X-rays:
Geographic lytic lesion IA/IB margin of sclerosis
Usually Eccentric more often than Central in the bone
Rarely expansile (rarely penetrates the cortex)
Calcified chondroid matrix 30%-50% of cases
Often better detected with a CT Scan
Periosteal Reaction 30-50% of cases
Usually occurs in Adjacent Diaphysis/Metaphysis since epiphysis is intraarticular and not surrounded by periosteum
MRI:
Geographic, well circumscribed lesion in the epiphysis
Intermediate Signal on T1
High signal on T2 mixed with low signal areas (low signal areas proposed to be secondary to lysosomal content of highly cellular areas)
Fluid/Fluid levels demonstrated in tumors that have undergone ABC change (aneurysmal bone cyst change)
Extensive Surrounding edema is common
Joint effusion in 30-50% of cases
CT scan:
Most useful for detecting subtle mineralization that is not apparent on X-rays
Useful for identifying intact periosteum around any expansile soft tissue component that appears as a surrounding thin reactive shell of bone/mineralization (Egg Shell Rim of Calcification). This helps place the tumor in a benign category.
Can help evaluate bony quality, extent of bone and cortical destruction and whether the subchondral plate of bone adjacent to the joint cartilage has been destroyed or is intact.
Bone Scan: Chondroblastomas demonstrate intense increased uptake on a bone scan
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Geographic Lesion
Epiphyseal Lesion
Skeletally Immature
Surrounding Sclerotic Rim
No Mineralization Detected on Radiograph |
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Plain X-Ray:
Chondroblastoma of Proximal Humerus
CT: Proximal Humerus Chondroblastoma
Subtle calcifications detected on CT that were not detected on plain X-ray
(Left arrow) Expansile Lesion: Periosteum Intact around Soft Tissue Component
(Right arrow) Subtle Calcification in Tumor
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Calcifications
Geographic
Epiphyseal
Expansile
Benign Aggressive Tumor
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 | CT Scan of Proximal Humerus Chondroblastoma
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Low Signal Areas
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Border
Edema
| MRI T2 Weighted Image: Lesion with Primarily High Signal with Low Signal in Many Areas and Extensive Surrounding Edema Chondroblastomas are often associated with extensive surrounding edema
MRI T2 Weighted Axial Image Extensive Peritumoral Edema
Bone Scan:
Increased Uptake in Chondroblastoma of Right Proximal Humerus
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Chondroblastoma Proximal
Tibia
Epiphyseal
Geographic
Subtle Surrounding Sclerosis |
Plain X-ray of Chondroblastoma of Proximal Tibia
Plain X-ray:
Proximal Tibia Chondroblastoma
Lateral Xray:
Chondroblastoma from Tibial Eminence: Expansile with Peripheral Rim of Calcification (Periosteum Intact)
CT Scan:
Expansile Chondroblastoma of Proximal Tibia Epiphysis with Intact Periosteum
CT Scan:
Expansile Chondroblastoma of Proximal Tibia: Subtle Calcifications within Tumor
CT Scan: Chondroblastoma of Proximal Tibia
Geographic Lesion of Proximal Tibia
MRI T1 Weighted Image
Proximal Tibia Chondroblastoma
Intermediate Signal on T1 Weighted Image
Chondroblastomas are primarily high signal on T2 with low signal areas in tumor
There is also extensive Peritumoral Edema and a knee Joint effusion
The tumor is well circumscribed
The periosteum is intact around the expansile soft tissue component |
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MRI T2 Weighted Image
Chondroblastoma of Proximal Tibia
Bone Scan:
Increased Uptake in Proximal Tibia Chondroblastoma
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Geographic Tumor Epiphysis |
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Subtle Mineralization Tumor
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Plain X-Ray and CT Scan:
Chondroblastoma of Proximal Tibia
Plain X-Ray:
Chondroblastoma of Proximal Humerus
MRI:
Proximal Humerus Chondroblastoma
Plain X-Ray:
Chondroblastoma of Toe Proximal Phalanx
Plain X-Ray:
Chondroblastoma of Talus
 Plain X-Ray:
Chondroblastoma of Talus
CT Scan:
Chondroblastoma of Talus
CT Scan:
Chondroblastoma of Talus
MRI T1:
Chondroblastoma of Talus
CT Scan:
Distal Femur Chondroblastoma
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Geographic Tumor
Epiphyseal Location
Subtle Calcifications |
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MRI T1 and T2 Weighted Images
Chondroblastoma of Distal Femur
GROSS PATHOLOGY
Grossly variable appearance
Grey/yellow/brown and gritty if has interspersed calcifications
Interspersed red areas from hemorrhagic necrosis
May be blue-grey areas from the chondroid matrix
Rim of sclerotic bone is visible in totally resected specimens
Lesion may be fully cystic with solid foci of tumor tissue at periphery
May undergo aneurysmal bone cyst change (ABC change)
Specimen:
Curettings
MICROSCOPIC PATHOLOGY
Variable appearance depending on percentage of cells, necrosis, cartilage matrix formation and ABC change
Hypercellular Tumor; Minimal Pleomorphism; Occasional Mitoses but no Abnormal Mitoses; No Atypia
Chondroid matrix in up to 15% of tumor
ABC component 5-15% of tumors
The tumor is composed of chondroblasts that have a distinct, thick cell membrane. The thick cell membrane gives it a "Chicken Wire Fence Appearance" especially when the cell membranes are calcified. "Chicken Wire Calcifications"
Cytoplasm of chondroblasts is plump, clear, eosinophilic
Nucleus is centrally or eccentrically round/oval with indentations
Coffee Bean Shaped Nucleus
Nucleus exhibits clefts, grooves, invaginations
Cells are closely packed together
Osteoclast-like giant cells are interspersed
Calcification is an important diagnostic sign and deposits itself along cell membranes. This gives a pattern referred to as a "Chicken Wire pattern of Calcification" because the appearance is similar to a chicken wire fence.
Chondroblasts stain positive for S-100
Microscopic Pathology:
Chondroblastoma
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Tightly Packed Cells
Dark, Thick Cell Membrane
Bean Shaped Nuclei
Abundant Cytoplasm
No Peomorphism
No Atypical Mitotic Figures |
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Chondroblast: Prominent Indented Nucleus
Plump Eosinophilic Cytoplasm
Thick Cell Membrane
Uniform Appearance of Cells |
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Imagine the cells present without the nuclei: The thickened cell membranes would give a chicken wire fence appearance
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Giant cells can be present
Chicken Wire Pattern of Calcification
The calcium is deposited along the cell membrane and perimeter of the cells in a linear manner
Von Kossa Stain for Calcium
S100 Protein Immunostain is Positive in Chondroblastoma
Cartilage stains positive for S-100
BIOLOGICAL BEHAVIOR
Chondroblastomas are benign aggressive tumors. They grow aggressively and destroy the bone. Chondroblastomas can destroy the cortex and grow into the soft tissues. They are contained by the periosteum (this differs from a malignant tumor that destroys the cortex)
There are extremely rare cases where chondroblastomas metastasize to the lungs and may not appear for 30 years
Metastases may remain stable or may progress and cause death
Recurrences may occur in the bone or adjacent soft tissue
Rare cases of multifocal chondroblastomas have been documented
Synchronous involvement of several sites
Secondary aneurysmal bone cyst frequently correlated with chondroblastoma
Chondroblastomas have been reported to transform into fibrosarcoma or osteosarcoma years after being treated with radiation.
TREATMENT
Intralesional curettage resection and bone grafting is the most common treatment. Cement and internal fixation may also be used to fill the defect after removal for selected patients.
High risk of local recurrence after curettage alone
Local adjuvants such as cryosurgery (liquid nitrogen application) may be considered to
decrease the risk of local recurrence.
Local recurrence results in further bony destruction
Rarely chondroblastomas that have grown out of control have required amputations for
treatment because they have completely destroyed the bone and/or adjacent joint.
In patients who are skeletally immature (still growing) there is always a risk of growth plate
failure from the chondroblastoma since it usually grows adjacent to the growth plate and may
damage it.
CT Guided Radiofrequency Ablation (Minimally Invasive Approach)
May be indicated for selected small tumors
Mostly performed in specialized centers
Treatment of a Chondroblastoma of Proximal Humerus with Intralesional Curettage Resection, Cryosurgery and Bone Grafting
Specimen: Curettings
Tumor Cavity: Periosteum Intact and Rotator Cuff Preserved
Tumor Cavity after Curettage
Cryosurgery of Tumor Cavity
Bone Grafting and Closure
Intralesional Curettage Resection, Cryosurgery and Cement/Internal Fixation for Chondroblastoma of Proximal Tibia
Surgery: Curettage Resection of a Proximal Tibia Chondroblastoma
Cryosurgery
Reinforcement of ACL Insertion
Cementing and Bone Graft
Bone Graft to Close Cortical Window
PROGNOSIS
Chondroblastomas are benign aggressive tumors that grow and destroy the bone and joint as it grows.
Most patients are cured with the first surgery
There is a significant risk of local recurrence (up to 30% with an intralesional curettage alone without an additional local adjuvant such as cryosurgery). Microscopic tumor cells can grow back after the tumor is removed.
My preferred method is to perform curettage and cryosurgery whenever feasible in appropriate cases in order to help eradicate microscopic disease and decrease the risk of local recurrence (decrease the risk of the tumor coming back in the bone after surgery)
Radiofrequency has been successful in the treatment of very selected small tumors.
This is a minimally invasive approach
Rare cases of pulmonary metastases have been reported.
Pulmonary metastases may be stable or may progress and cause death
Pulmonary metastases have extremely rarely been reported to develop 30 years after initial
treatment.
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