Osteochondroma & Multiple Hereditary Exostosis

Question 1

What is the difference between osteochondroma and multiple hereditary exostosis?

Answer 1

Osteochondroma is a solitary benign chondrogenic lesion derived from aberrant cartilage from the perichondral ring; MHE is multiple osteochondromas

Question 2

What are common locations for osteochondromas and MHE?

Answer 2

knee, proximal femur, proximal humerus, subungal (most commonly the hallux)

Question 3

Mutations in the EXT 1, 2, and/or 3 genes leads to what?

Answer 3

Multiple hereditary exostosis; affects prehypertrophic chondrocytes

Question 4

What are the most common sites of deformities of MHE?

Answer 4

1) knee
2) forearm
3) ankle

Question 5

What are the most common deformities with MHE?

Answer 5

1) Ulnar shortening and radial bowing
2) radial head dislocation
3) ulnar deviation of hand

Question 6

What are imaging and histological characteristics in osteochondromas and MHE?

Answer 6

1) Sessile or pedunculated lesions on surface of bones
2) histology similar to physis
3) can have cartilage cap (if thickens in adulthood, worried about malignancy)

Question 7

When is surgery an option for osteochondromas or MHE?

Answer 7

1) Osteochondroma- symptomatic lesions (delay until maturity)
2) MHE- radial head dislocation, loss of prono/supination

Question 8

What is the recurrence rate of osteochondroma or MHE after resection?

Answer 8

2-5%