Access Keys:
Skip to content (Access Key - 0)

Osteochondroma

Tumor biology and incidence

  • Benign lesions originating from bone; grow outwards against adjacent tissue
  • Most common benign skeletal tumor; accounts for 40% of all benign bone tumors

Age

Affects persons 10-35 years of age

Gender

M:F = 2:1

Associated syndromes

Familial osteochondromatosis

Presentation

  • Non-painful mass or bump
  • Can be symptomatic if lesion:
    • Caused by impingement on surrounding structures (nerves, vessels, musculotendinous structures, bones)
    • Fractures (rare)
    • Associated with bursa formation in areas of soft tissue friction, such as near or beneath the iliotibial band
    • Undergoes sarcomatous transformation
  • Growth of the lesion usually ceases at maturity
  • Painful lesions or lesions that grow rapidly may be undergoing malignant transformation (occurs in less than 1% of cases), especially if pain and growth occur after skeletal maturity

Physical findings

  • Painless, firm mass fixed to underlying bone can often be palpated
  • May be able to elicit Tinel's sign if adjacent nerves are involved
  • Mechanical features – catching or snapping – can be reproduced if osteochondroma impinges on soft tissue.

Plain films

Site
  • Most commonly found at the knee, shoulder and hip
  • Generally metaphyseal
  • Arises from cortical surface, classified as a surface (parosteal) lesion
  • Typically grows perpendicular to cortex and away from epiphysis
  • Cortical surfaces and marrow cavity of lesion are contiguous with underlying bone
  • Always check for presence of other lesions (ie, familial osteochondromatosis)
Size
  • May be small or large lesions
  • Sessile lesions do not extend far from cortex; pedunculated lesions may have a long "stalk"
Tumor effect on bone

Lesion may expand, remodel entire shape of metaphyseal bone

Bone response to tumor

None

Matrix
  • Periphery of lesion is corticated by process of endochondral ossification
  • Cartilagenous matrix may be seen within cartilage cap prior to skeletal maturity
Cortex
  • Intact
  • Inderlying cortex is contiguous with cortex of lesion
Soft tissue mass
  • Overlying cartilage cap usually eliminated by process of endochondral ossification at termination of skeletal growth
  • Thick non-ossified cartilage cap (> 1-2 cm) in an adult suggests malignant transformation

Bone scan

  • Increased uptake may be seen if osteochondroma is still remodeling
    • Increased uptake in a previously cold lesion suggests recent injury or malignant transformation
  • Bone scan useful for the assessment of multiple lesions

MRI

  • MRI extremely useful in evaluation of symptomatic lesions
    • Used to determine thickness of cartilage cap in evaluation of possible sarcomatous degeneration
    • Can readily identify complications including bursa formation, fracture, and possible neurovascular impingement

Differential diagnosis

  • Juxtacortical myositis ossificans
  • Periosteal chondroma
  • Surface (parosteal) osteosarcoma (low or high grade)
  • Chondrosarcoma arising from osteochondroma
  • Soft tissue osteosarcoma
  • Bizarre parosteal osteochondromatous proliferation
  • Extraskeletal myxoid chondrosarcoma
  • Tumoral calcinosis

Natural history

  • Considered benign, active lesions (Enneking stage 2) during active growth
  • Become benign, latent (stage 1 lesions) with the cessation of growth
  • Isolated osteochondromas rarely undergo malignant transformation (<1%); however, clinical suspicion should be raised in the presence of atypical features

Pathology

  • Gross: Exophytic lesion with cartilage cap usually less than 2cm in thickness.
  • Microscopic: Cartilage cap matures into trabecular bone; at interface, cartilage cores may be seen in trabeculae
  • Intertrabecular spaces contain adipose tissue or hematopoietic marrow
  • Lesion merges with underlying marrow
  • Cartilage cap may be replaced by bone over time.

Diagnosis and treatment

  • Conventional radiographs usually so classic that no biopsy is needed
  • General rules:
    • Asymptomatic: Do not need treatment
    • Excise if locally painful, if there is neurovascular compromise (for example, in the popliteal fossa), or if there is a change in the cartilage cap
    • Pain is an acceptable indication for resection in skeletally immature patients
      • Surgery may lead to deformity, depending on proximity to the growth plate
      • Lesions may recur if not completely excised

Complications

  • Malignant transformation may occur, usually to a low-grade chondrosarcoma or osteosarcoma
    • Risk is probably <1% for solitary lesions, higher for multiple lesions
    • Greater risk of transformation with more proximal lesions and those that grow post maturity
  • Bursa formation
  • Fracture
  • Neurovascular compromise

Recommended reading

Enneking W. Musculoskeletal Tumor Surgery Churchill Livingstone, New York, NY 1983.

J Natl Cancer Inst. 2007 Mar 7;99(5):396-406. The role of EXT1 in nonhereditary osteochondroma: identification of homozygous deletions. Hameetman L, Szuhai K, Yavas A, Knijnenburg J, van Duin M, van Dekken H, Taminiau AH, Cleton-Jansen AM, Bovée JV, Hogendoorn PC.

Schmale GA, Conrad EU 3rd, Raskind WH. The natural history of hereditary multiple exostoses. J Bone Joint Surg Am. 1994 Jul;76(7):986-92.

Peer Review

OrthopaedicsOne Peer Review Workflow is an innovative platform that allows the process of peer review to occur right within an OrthopaedicsOne article in an open, transparent and flexible manner. Learn more

Instructions for Authors

Read our Instructions for Authors to learn about contributing or editing articles on OrthopaedicsOne.

Content Partner

Learn about becoming an OrthopaedicsOne Content Partner.

Academic Resources

Resources on Osteochondroma from Pubget.

Error rendering macro 'rss' : The RSS macro is retrieving an HTML page.
Related Content

Resources on Osteochondroma and related topics in OrthopaedicsOne spaces.

Page: Osteochondroma (OrthopaedicsOne Articles)
Page: Osteoid osteoma (OrthopaedicsOne Articles)
Page: Unicameral bone cyst (OrthopaedicsOne Articles)
Page: Chondroblastoma (OrthopaedicsOne Articles)
Page: Fibrous dysplasia (OrthopaedicsOne Articles)
Page: Giant cell tumor (OrthopaedicsOne Articles)
Page: Osteoblastoma (OrthopaedicsOne Articles)
Page: Aneurysmal bone cyst (OrthopaedicsOne Articles)
Page: Eosinophilic granuloma (OrthopaedicsOne Articles)
Page: Multiple hereditary exostoses (familial osteochondromatosis) (OrthopaedicsOne Articles)
Showing first 10 of 449 results