Diagnosis and Modality:

  • Frontal radiograph of the right shoulder shows a broad-based exostosis with continuity of bone cortex and medullary marrow to the metaphysis of the humerus.

This is a classic radiographic appearance of ‘sessile osteochondroma’ at the most common location (metaphysis) of bone.


  • Due to aberrant epiphyseal development
  • Most common benign bone tumor
  • Growth stops after skeletal maturation
  • Malignant transformation in 1-2% of solitary lesion


  • Suspect malignant transformation if: growth after skeletal maturation, pain in the absence of fracture, bursitis or nerve compression
  • MRI and CT to demonstrate thickness of cartilaginous cap, if >2 cm suspect malignancy

Stoller et al. Diagnostic Imaging: Orthopedics. 2004

Case submitted by: Dr. Rathachai Kaewlai