Chondrosarcoma

Chondrosarcoma (Image sourced from Bristol Biomed Image Archive with permission)

• Any malignant neoplasm in which mesenchymal cells produce chondroid matrix
• May involve development of bone via metaplasia or endochondral ossification
• Most common in old dogs and sheep
• Occur in flat bones more frequently than others, especially pelvis, nasal cavity, sternum and ribs
• Slower growth rate, longer clinical course and later to metastasize than OSA
• Metastatic rate is slow and around 20%
• Grossly:
  • With time become large, lobulated
  • Grey-blue on cut surface
  • May involve haemorrhage and necrosis or be gelatinous
• Histologically:
  • High cellularity
  • May be well differentiated and resemble chondroma or contain anaplastic cells with only small areas of differentiation
  • Lacunae contain large cells, sometimes with double nuclei
  • Mitosis is common