Age / Sex : 54 / M

Chief complaint : upper arm pain


What is your diagnosis?

Two weeks later, you can see the final diagonosis with a brief discussion of this case (Please submit only one answer)

Courtesy : 이슬기 (Seul Ki Lee), 성빈센트 병원(St. Vincent’s Hospital)

Dedifferentiated chondrosarcoma

Discussion

Findings
1. Plain radiograph shows an extensive mixed lytic and sclerotic lesion in the humerus with endosteal scalloping. Note the chondral-type mineralization in the intramedullary cavity and the densely osteoid-type mineralization at the juxtacortical area.
2. Axial CT scan reveals the intramedullary chondral-type mineralization and the juxtacortical dense osteoid-type mineralization
3. Coronal T2 and enhanced T1 images with fat suppression show lobulated high signal intramedullary lesion with peripheral and septal enhancement. Note the osteoblastic extraosseous extension.
4. Axial T2 and enhanced T1 images with fat suppression also show intramedullary lesion with extraosseous extension. Note the small bone metastasis in the adjacent rib (arrow).

References
Radiographic, CT, and MR imaging features of dedifferentiated chondrosarcomas: a retrospective review of 174 de novo cases Radiographics. 2004 Sep-Oct;24(5):1397-409