Chondrosarcoma (central)

Tumor biology and incidence

• Primary malignant tumor whose cells produce cartilage matrix
• May arise de novo or secondarily to an existing benign cartilaginous tumor (usually enchondroma or osteocartilaginous exostosis)
• 17% of primary malignant bone tumors
• Most common sites
  • Pelvis 30%
  • Femur 20%
  • Femoral head 10%
  • Ribs 10%

Age

• Peak incidence 30 – 60 years
• Secondary chondrosarcoma typically in younger patients, ages 20-40 years

Gender

M:F = 2:1

Classification

• Central (high grade or low grade)
• Periosteal
• Clear cell
• Mesenchymal
• Dedifferentiated

Presentation

• Most common malignant tumor of the hands and face in middle aged patients
• Usually occurs in the metaphysis or diaphysis
• Presents with constant ache or increased size of a pre-existing lump
• Nerve dysfunction (sciatic, femoral, or lumbrosacral plexus) may occur with pelvic lesions
• Pathologic fracture possible, but uncommon
• Metastatic deposits are infrequent and usually go to lung
• Patients with Ollier’s disease (multiple enchondromatosis) or Maffucci’s syndrome (multiple enchondromas and hemangiomas) at much higher risk of chondrosarcoma than the normal population

Plain films

• Usually diagnosed by appearance on plain x-rays
• Diagnostic features of secondary malignant degeneration of a benign cartilage tumor include:
  • Evidence of soft tissue calcification or soft tissue mass
  • Endosteal erosion and permeative features in an enchondroma
  • Growth in a previously stable exostosis
  • Expansion of cartilage cap of an exostosis

Site

Proximal and distal femur, proximal humerus or scapula, and pelvis are most common (75% of lesions); ribs and sternum less common; lesions distal to wrist or ankle rare

Size

Variable; can be larger than 5 cm

Tumor effect on bone

• Relatively geographic bony lesions, although permeative regions of bony destruction common
• Extent of bone destruction generally correlates with lesion’s histologic grade

Bone response to tumor

Endosteal expansion; results from periosteal expansion in response to endosteal erosion

Matrix

• Variable amounts of internal punctate calcifications
• Popcorn, comma-shaped calcifications

Cortex

• Endosteal scalloping and thinning
• Cortical thickening may be present with endosteal expansion
• Complete cortical destruction may be present (more common with higher-grade lesions)

Soft tissue mass

• May be present
• Matrix formation may be present in soft tissues

Bone scan and chest CT

Necessary for systemic staging

CT scan

May be helpful in detecting subtle matrix calcification

MRI

Best for local staging of tumor extent

Differential diagnosis

• Enchondroma
  • More common when location is metaphyseal-diaphyseal in long bone
• Osteosarcoma
• Fibrosarcoma
• Malignant fibrous histiocytoma
• Metastases
• Chordoma
  • If sacrum is involved

Natural history

• Cartilage tumors in more distal locations usually benign
• Histologic grade determines risk of metastases
• Usually lower-grade chondrosarcoma when lesion arises in an enchondroma or osteochondroma
• Patients with local recurrence of pelvic lesions have poor prognosis for cure
• Lung metastases may occur years after presentation
• Metastasis to regional lymph nodes is rare

Pathology

• Gross: Myxoid or chondroid appearance
• Microscopic: Chondroid matrix; shows increased cellularity, has binucleate cells
  • Degree of cellularity, cytological atypia depends on tumor grade
• Myxoid change may be present
• Mitoses rarely seen

Diagnosis and treatment

• Biopsy, in consultation with a musculoskeletal surgical oncologist
• Difficult to distinguish between low-grade chondrosarcoma and benign enchondroma based on pathology alone; diagnosis aided by clinical and radiographic data
• Treatment: surgical resection with wide margins
• Radiation and chemotherapy not effective for primary management
  • Radiation appropriate for palliation or for surgically inaccessible lesions
  • Radiation may be used before or after microscopically incomplete resections in spine or pelvis; complete surgical resection best treatment, though
• Disease free survival following complete resection: about 30% at 5 years for high-grade chondrosarcoma to greater than 90% for low-grade tumors