Osteochondroma




CLINICAL SUMMARY


Osteochondromas are disorders of physeal bone growth in which histologically normal bone grows transversely away from the center of the growth plate. The large majority of patients with osteochondromas present with a single lesion, and in the absence of mechanical pain, no treatment is required.




DIAGNOSTIC FEATURES





















History


  • Young patients—75% are younger than 20 years of age



  • Typically presents as a painless mass



  • Pain, if present, is usually due to mechanical effect on adjacent structures, infrequently due to fracture of a pedunculated lesion

Location


  • Metaphyseal, juxtacortical, and exophytic



  • Distribution: most common about the knee and femur (30%), tibia (20%), humerus (20%), hand and foot (10%)

Margins


  • Nonlytic lesion



  • Cortical and marrow continuity with underlying bone confirms diagnosis

Matrix


  • Cap contains hyaline cartilage; underlying bone is normal in appearance






IMAGING
































  • Sessile proximal humerus osteochondroma demonstrating typical marrow and cortical continuity ( left ).



  • Pedunculated osteochondroma in distal femur ( right ).



  • Osteochondromas usually point away from the adjacent growth plate or joint.










  • Asymptomatic sessile femoral osteochondroma in a toddler ( left ).



  • Lesion causing activity-related pain and limitation of pronation and supination, arising from diaphyseal radius ( right ).










  • Coronal T1 MRI demonstrates diagnostic marrow and cortex continuity of a pedunculated osteochondroma in the proximal tibia ( left ).



  • Corticomedullary continuity is seen on CT in the proximal humerus ( right ).


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