Which single radiographic feature is MOST specific for distinguishing an osteochondroma from other metaphyseal bone lesions?
- A Location in the metaphysis of a long bone
- B Presence of a cartilaginous cap thicker than 1 cm in an adult
- C Continuity of the cortex and medullary cavity of the lesion with the parent bone ✓
- D Growth of the lesion away from the adjacent joint
Correct answer: C. Continuity of the cortex and medullary cavity of the lesion with the parent bone
Explanation
By definition, an osteochondroma is a developmental anomaly in which the lesion's cortex and medullary cavity are continuous with those of the parent bone; this feature is diagnostic on plain film or CT. Metaphyseal location and orientation away from the joint are typical but not specific. A cartilage cap thicker than 1 to 2 cm after skeletal maturity suggests malignant transformation to chondrosarcoma, not the diagnosis of osteochondroma itself.
Reference: Radiology Review Manual, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.