OSTEOCHONDROMA Cartilage capped exostosis Commonest benign tumour of bone Metaphyseal developmental abnormality D FRANTZEN OSTEOCHONDROMA

INCIDENCE 45 % of benign bony tumours 12 % of all bony tumours Become evident < 20 yrs Solitary or multiple Any enchondral ossification bone D FRANTZEN OSTEOCHONDROMA

CLINICALLY Lump or mechanical problem Tendon or nerve irritation Sessile or pedunculated 50% distal femur, proximal tibia, proximal humerus D FRANTZEN OSTEOCHONDROMA

CLINICAL Active growth during puberty Move towards diaphysis during growth Excise if troublesome in second decade D FRANTZEN OSTEOCHONDROMA

RADIOLOGY Flat/ sessile / pedunculated Tumour blending into metaphysis Pedunculated orientated proximally Cartilage cap with calcification D FRANTZEN OSTEOCHONDROMA

PATHOLOGY Normal bone covered by normal cartilage cap Cartilage cap resembles normal growth plate Cartilage more disorganized D FRANTZEN OSTEOCHONDROMA

PATHOLOGY Covered by thin layer of periosteum Binucleate chondrocytes in lacunae D FRANTZEN OSTEOCHONDROMA

TREATMENT Nil required unless symptomatic Extra-capsular marginal excision Recurrence < 5% D FRANTZEN OSTEOCHONDROMA

PROGNOSIS Risk of malignancy if solitary - 0.2 % Risk of malignancy in diaphyseal aclasia : - 20 % Sarcomatous changes usually low- grade D FRANTZEN OSTEOCHONDROMA