What are the two morphological types of osteochondromas?
Sessile and pedunculated. Pedunculated is more common and seen around the knee, hip and ankle while sessile prefers the humerus.
Once radiological diagnosis is confirmed, what is the next step of investigation?
Nothing. Lesion may be serially followed up. There is no intervention required provided the cartilaginous cap remains within normal limits. Only if secondary effects due to compression on adjacent structures become clinically significant, patient may undergo some surgery.
What is the normal cut off of cartilage cap thickness in children and adults?
Children <3cm; adults <2cm.
What is the rare differential for this lesion?
Chondrosarcoma. Malignant degeneration of osteochondromas usually occur before 30 years of age whilst chondrosarcomas are seen >45 years of age.
No interval changes in one year. No increase in cartilaginous cap thickness. Subtle subchondral marrow hyperintensity seen.