Bone Pathology Database

Teaching Version


Text in Italics is general (instructional) information

Return to base page

2nd image
X ray
Third image
AP X ray
The lateral X ray shows a bony outgrowth on the posterior aspect of the distal femur. The trabeculae in this bony mass appear orgainised and are in continuity with those in the femur.
Because this lesion was symptomatic it was excised.

The cartilage capped subperiosteal bone projection accounts for 20-50% of benign bone tumors.
Osteochondromas can either be flattened (sessile) or stalk-like (exostosis) and appear in a juxta-epiphyseal location. The lesions occur only in bones that develop from cartilage (endochondral ossification). After the close of the growth plate in late adolescence there is normally further growth of the osteochondroma.

Pain in a osteochondroma should be considered a need for further investigation:

Causes of pain in an ostochondroma

  1. Fracture of the stalk of a pedunculated lesion
  2. Mechanical irritation - muscle, tendon etc
  3. Nerve irritation
  4. Malignant change (to chondro or osteosarcoma)

Hereditary multiple osteochondromatosis is an autosomal dominant condition that can lead to both sessile and pedunculated lesions. The lesions may occur on different bones or on the same bone, and symptoms present in the first decade of life.

The risk of malignant transformation to chondrosarcoma in hereditary multiple osteochondromatosis is unknown, but may be 25-30% compared to approximately 1% for a solitary osteochondromas.3 The risk of malignant degeneration increases as the number and size of the osteochondromas increases. In general, a sessile lesion is more likely to degenerate into sarcoma than an exostosis. A large cartilage cap ( over 2 cm of cartilage) on Magnetic resonance or Computer tomogramme are suggestive of malignant change.


Not usually necessary unless symptomatic. Multiple osteochondromatiosis needs regular followup because of risk of malignant change. Painful lesions need excision. Regular radioisotope bone scans are recommended in these cases. Problem lesions will appear as a hot spot.


Record 102