Radiological appearance of bone tumours

When looking at a radiograph of a possible bone tumour one should consider the following points:

• is the lesion lytic or sclerotic ?
  
  
• is the cortex intact, eroded or broken ?
  
  
• is the cortex indented? If so, from outside or inside ?
  
  
• is the medullary cavity wider than normal ?
  
  
• is there a Codman's triangle ?
  
  
• if the tumour is fusiform, is there an onion skin appearance ? suggests Ewing's tumour
  
  
• is there any sunray calcification ? suggests an osteogenic sarcoma