Compared with a solitary osteochondroma, the risk of malignant transformation into chondrosarcoma in patients with hereditary multiple exostoses (diaphyseal aclasis) is approximately:
- A Equal in both conditions, about 15 percent
- B 5 percent versus 50 percent
- C <1 percent versus 5 to 10 percent ✓
- D Nil in either condition, as transformation does not occur
Correct answer: C. <1 percent versus 5 to 10 percent
Explanation
Solitary osteochondroma carries a very low risk of malignant transformation, generally quoted as less than 1 percent. In hereditary multiple exostoses, an autosomal dominant condition caused by EXT1 or EXT2 mutations, the cumulative risk rises to approximately 5 to 10 percent, usually at the shoulder or pelvis girdle. Transformation is suspected when the cartilage cap thickens beyond about 2 cm in an adult or the lesion grows after skeletal maturity.
Reference: Apley and Solomon's System of Orthopaedics and Trauma, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.