Hereditary multiple exostosis

Case contribution: Dr Radhiana Hassan


  • A 9 years old boy
  • Multiple swelling at limbs
  • No symptoms of compression
  • No rapid progression of swelling
  • Clinically presence of multiple bony-hard swelling at left elbow region, knee and proximal tibia noted.
  • Valgus knee left 5 degree and right 2 degree.
  • Limited pronation and supination of left forearm.
Radiograph of left femur in AP and lateral views
Radiograph of bilateral forearm in AP and lateral views

Radiographic findings:

  • Multiple bony projection seen distal femur, proximal tibia and distal radius ulna (worse on the left side)
  • The bony outgrowth is seen projecting away from the joint line
  • No cortical break is seen
  • No surrounding soft tissue mass, however bulge of soft tissue seen at the region of bone outgrowth. No calcification within the soft tissue.
  • No fracture.

Diagnosis: Hereditary multiple exostoses


  • Exostoses are defined as benign growths of bone extending outwards from the surface of a bone.
  • Where exostoses are capped with cartilage, they are termed osteochondromas, which can be solitary or multiple, sessile or pedunculated
  • Hereditary multiple exostoses, also known as diaphyseal aclasis or osteochondromatosis.
  • It is an autosomal dominant condition characterized by the development of multiple osteochondromas.
  • Most patients are diagnosed by the age of 5 years, and virtually all are diagnosed by the age of 12 years.
  • The skeletal distribution of lesions varies with some show typical bilateral and symmetric distribution, whereas others show a strong unilateral predominance.
  • Complications include vascular impingement, neural impingement, fracture, bursitis, deformity and ankylosis.
  • Malignant transformation is more common than in sporadic cases, with transformation rates reported as high as 25%.

Progress of patient:

  • Worsening left genu valgus secondary to multiple exostosis
  • Left medial hemiepiphysiodesis done


  • Hereditary multiple exostoses. Radiopedia at
Author: radhianahassan