Case 6 Answer

Giant Cell Tumor of Bone

Findings:
- Classic location: knee or distal radius (~75%)

- eccentric - abuts articular surface with closed growth plate 

- thins overlying cortex 

- narrow zone of transition with non sclerotic borders 

- no internal matrix 

- +/- soft tissue mass 

reference: https://radiopaedia.org/articles/giant-cell-tumour-of-bone?lang=us