In osteochondroma, which radiographic feature is most typical?

• A. Ultrasound shows a soft tissue extension
• B. A bony projection pedunculated or sessile that is continuous with the cortex and medullary canal
• C. A lesion with a sunburst periosteal reaction
• D. A lytic lesion with poorly defined margins

Answer: (B)

Osteochondroma has a distinctive relationship to the bone it arises from. On radiographs, you see a bony projection that is continuous with the cortex and with the medullary canal of the parent bone. This cortex–medullary continuity, whether the lesion is pedunculated (stalk-like) or sessile (broad-based), is the hallmark feature. It reflects that the growth originates from the metaphysis near the growth plate and expands outward while preserving the internal bone architecture.

Other patterns don’t fit osteochondroma. A sunburst periosteal reaction suggests an aggressive process like osteosarcoma. A lytic lesion with poorly defined margins also points toward malignancy or infection. Ultrasound showing a soft tissue extension would indicate a lesion with a prominent soft-tissue component rather than a discrete osseous outgrowth with continuous cortex and medullary canal.