CLASSIFICATION
1. Primary Chondrosarcoma (90%)
Arises de novo in normal bone.
A. Central (Intramedullary) (99%)
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Conventional chondrosarcoma (85–90%)
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Grade 1: 30%
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Grade 2: 40%
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Grade 3: 30%
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Dedifferentiated chondrosarcoma: 8%
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Clear cell chondrosarcoma: 4%
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Mesenchymal chondrosarcoma: 1%
B. Peripheral (1%)
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Periosteal (juxtacortical) chondrosarcoma
2. Secondary Chondrosarcoma (10%)
Arises from pre-existing bone lesions:
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Enchondroma
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Osteochondroma
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Ollier disease
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Maffucci syndrome
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Fibrous dysplasia
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Paget disease of bone
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Chondroblastoma
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Radiation-induced lesions
CONVENTIONAL CHONDROSARCOMA
Clinical Presentation
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Pain with or without a palpable mass
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Pathological fracture is uncommon
Epidemiology
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Male predominance (2:1)
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Most common primary bone sarcoma in adults
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Second most common primary malignant bone tumor overall
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Accounts for approximately 20% of malignant bone sarcomas
Age Distribution
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Peak incidence between 50 and 70 years
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Rare before 40 years of age
Common Sites
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Proximal femur
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Distal femur
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Proximal humerus
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Pelvis
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Scapula
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Ribs
Rare sites:
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Spine
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Craniofacial bones
RADIOGRAPHIC FEATURES
Location
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Metaphysis or diaphysis
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Rarely epiphyseal
Matrix Calcification
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Characteristic ring-and-arc or stippled calcification
Low-Grade Lesions
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Uniform calcification
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Well-defined margins
High-Grade Lesions
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Large non-calcified areas
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Irregular, ill-defined margins
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Frequent soft tissue extension
Radiological Features Suggestive of Malignancy
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Expansion of bone contour
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Cortical thickening
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Permeative pattern
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Endosteal scalloping
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New lytic areas adjacent to calcification
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Cortical destruction
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Soft tissue extension (definitive sign of malignancy)
DIAGNOSTIC DILEMMA
Enchondroma vs Low-Grade Chondrosarcoma (Long Bones)
Enchondroma
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Common in hands and feet
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Occurs in long bones (especially femur)
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Rare in pelvis and axial skeleton
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No associated soft tissue mass
Chondrosarcoma
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Common in axial skeleton and pelvis
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Occurs in long bones
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Rare in hands and feet
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May or may not have a soft tissue mass
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Low-grade lesions often lack soft tissue extension
Long Bone Enchondroma: Typical Features
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Age less than 50 years
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Pain not attributable to lesion
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Size less than 5 centimeters
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Bone scan uptake equal to or less than anterior superior iliac spine
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Commonly diaphyseal
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Minimal endosteal scalloping
Features Favoring Chondrosarcoma
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Age greater than 50 years
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Pain attributable to lesion
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Size greater than 5 centimeters
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Bone scan uptake equal to or greater than anterior superior iliac spine
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Endosteal scalloping greater than two-thirds cortical thickness
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Cortical thickening
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Periosteal reaction
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Possible soft tissue mass
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Epiphyseal extension
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Peripheral and septal enhancement on magnetic resonance imaging
HISTOLOGIC GRADING (CONVENTIONAL)
Grade 1 (Low Grade)
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Ring-and-arc calcification
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Mild bony expansion
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Size greater than 5 centimeters
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Deep endosteal scalloping
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Low cellularity
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Rare mitoses
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Entrapment of pre-existing trabeculae
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Occasional binucleation
Grade 2 (Intermediate Grade)
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Lytic lesion with surrounding sclerosis
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Subtle intralesional calcification
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High signal intensity on T2-weighted magnetic resonance imaging
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Soft tissue component
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Permeative growth
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Deep endosteal scalloping
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Markedly increased uptake on bone scan
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Metastasis rate up to 33%, commonly to lungs
Grade 3 (High Grade)
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Predominantly lytic lesion
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Marked bony expansion
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Cortical destruction
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Aggressive local behavior
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Metastasis in up to 70% of cases, most commonly to lungs and bone
SECONDARY CHONDROSARCOMA
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Most commonly arises from osteochondromas
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Common sites:
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Scapula
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Ribs
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Pelvis
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Proximal femur
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Majority are low grade
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Often curable with wide excision
Features Suggesting Malignant Transformation
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Cartilaginous cap thickness greater than 2 centimeters on magnetic resonance imaging
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Cortical destruction
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Back-growth of cartilage into stalk or medullary canal
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Lysis of calcification within cartilage cap
DEDIFFERENTIATED CHONDROSARCOMA
Pathology
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Biphasic tumor consisting of:
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Low-grade chondrosarcoma
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High-grade non-cartilaginous spindle cell sarcoma
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Sharp and abrupt demarcation between components
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Sarcoma component may resemble:
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Undifferentiated pleomorphic sarcoma
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Osteosarcoma
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Fibrosarcoma
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Clinical Features
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Age greater than 50 years
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Common sites:
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Pelvis
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Proximal femur
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Proximal humerus
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Distal femur
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Ribs
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Radiology
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Biphasic appearance:
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Chondroid region
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Aggressive lytic region
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Soft tissue mass in approximately 70%
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Abrupt transition between components
Prognosis and Treatment
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Extremely aggressive
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High metastatic rate
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Wide or radical resection
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Amputation may be required
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Chemotherapy may be considered but benefit is unclear
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Approximately 90% mortality within 2 years
CLEAR CELL CHONDROSARCOMA
Characteristics
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Low to intermediate grade malignancy
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Neoplastic chondrocytes with abundant clear cytoplasm
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Minimal cartilaginous matrix
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Metastasis rate approximately 15%, mainly to lungs
Clinical Features
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Age 20 to 40 years
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Predominantly epiphyseal location
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Common sites:
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Proximal femur
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Proximal humerus
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Distal femur
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Proximal tibia
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Imaging
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Osteolytic expansile epiphyseal lesion
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Possible focal calcification
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Thin but intact cortex
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Rare soft tissue extension
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Intermediate signal on T1 and high signal on T2 magnetic resonance imaging
Histology
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Large clear cells with sharp cell borders
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Glycogen-rich cytoplasm
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S-100 and periodic acid–Schiff positive
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Occasional osteoid deposition
Treatment and Prognosis
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Wide excision recommended
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Curettage associated with 80% recurrence
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No role for chemotherapy or radiotherapy
MESENCHYMAL CHONDROSARCOMA
Characteristics
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High-grade malignant cartilage-forming tumor
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Small round or spindle cells with islands of malignant cartilage
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Hemangiopericytoma-like vascular pattern
Clinical Features
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Age 10 to 40 years
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Occurs in bone and soft tissue
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Common sites:
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Femur
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Ribs
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Spine
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Maxilla
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Mandible
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Pelvis
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Radiology
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Permeative lesion
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Stippled calcification
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Cortical destruction
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Soft tissue extension
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Pathological fracture
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Codman triangle periosteal reaction
Histology
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Undifferentiated mesenchymal cells
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Scattered low-grade cartilage islands
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Highly vascular staghorn pattern
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Chromosomal translocation similar to Ewing sarcoma
Behavior and Management
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Highly aggressive
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Metastasis to lungs, lymph nodes, bone, and viscera
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Approximately 70% mortality
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Managed with surgery and chemotherapy
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Radiotherapy in selected cases
JUXTACORTICAL (PERIOSTEAL) CHONDROSARCOMA
Definition
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Malignant subperiosteal cartilaginous tumor
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No osteoid production
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Causes cortical erosion without medullary involvement
Clinical Features
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Most patients older than 20 years
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Painless mass or swelling
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Pain in approximately one-third of patients
Radiographic Features
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Metaphyseal location
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Saucer-shaped cortical erosion
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Chondroid matrix calcification
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Sclerotic triangular margin
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Average size approximately 11 centimeters
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Intramedullary canal preserved
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No hair-on-end periosteal reaction
Common Sites
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Femur
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Humerus
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Pelvis
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Ribs
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Foot
Treatment and Prognosis
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Wide limb-sparing resection
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No chemotherapy or radiotherapy
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Long-term survival rate 80 to 90%
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