Chondroblastoma




Codman Tumor


CLINICAL SUMMARY


Chondroblastoma is an uncommon bone tumor, found almost exclusively in the epiphysis of long bones or epiphyseal equivalents, such as an apophysis or the patella. Diagnosis sometimes is obscured by synovitis in the adjacent joint. Curettage (intralesional excision) is usually curative. Rarely, lung metastases are found.




DIAGNOSTIC FEATURES





















History


  • A large majority (90%) occur between 5 and 25 years of age



  • Rare after physis is closed



  • Persistent periarticular pain



  • Sometimes presents with secondary synovitis and joint effusion

Location


  • Almost exclusively originates in epiphysis (or an epiphyseal equivalent, e.g., apophysis or patella)



  • Distribution: most common in proximal femur (25%) and distal femur (20%)

Margins


  • Geographic lysis, often with thin sclerotic rim



  • Rarely, expansile remodeling

Matrix


  • Subtle chondroid mineralized matrix



  • Approximately one third will have a secondary aneurysmal bone cyst component






IMAGING
























  • Chondroblastoma is eccentric within the epiphysis more often than central, as seen in this femoral head lesion ( left ).



  • A proximal humerus chondroblastoma is visible in the epiphysis with a geographic lysis and a narrow zone of transition ( right ).


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