A radiograph of the right shoulder shows a large pedunculated lytic mass (long arrows) in the proximal metadiaphysis of the humerus, with continuous cortex and marrow cavity. Note areas of disrupted cortex (short arrows).
Facts: Osteochondroma
- Benign bone tumor usually recognized on radiography as a lesion perpendicular to the parent bone, with a continuous cortex and marrow cavity.
- Pain from an osteochondroma is commonly caused by fracture, burisitis or compression of surrounding structures. Malignant degeneration of a single osteochondroma is rare.
Facts: Malignant Transformation of Osteochondroma
- 1% of solitary osteochondroma, 20% of hereditary form
- If transformed, most are to chondrosarcoma
- Average age of malignant transformation = 30 years
Imaging Features Suggesting Malignant Transformation
- Clinical: 30 years old, location at pelvis and shoulder, increasing pain and mass at site of known osteochondroma
- Imaging: thick/irregular calcified cap, bone destruction, soft tissue mass, altered appearance on sequential studies
Our case: pedunculated osteochondroma in a middle-aged patient presenting with increasing pain, suspicious for malignant transformation. Awaiting pathologic results.
References:
1. Yochum TR, Rowe LJ. Essentials of Skeletal Radiology, 3rd ed. 2005
2. Tehranzadeh J. Musculoskeletal Imaging Cases, 2009
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