Which part of the bone is commonly affected in canine osteosarcoma?

Which part of the bone is commonly affected in canine osteosarcoma?

• A. Metaphysis
• B. Epiphysis
• C. Diaphysis
• D. Periosteum

Answer: (A)

Osteosarcoma arises from osteoblasts that lay down osteoid, so it loves places where bone formation is most active. In long bones, the metaphysis is the region just beside the growth plate where remodeling and osteoblastic activity are high and blood supply is abundant. That combination makes it the likeliest origin site for malignant osteoblasts to transform and start growing. Because of this, dogs commonly develop osteosarcoma starting in the metaphysis of weight-bearing long bones (like the distal radius, proximal tibia, distal femur, and proximal humerus). The epiphysis and diaphysis are less typical primary sites, and the periosteum is a tissue around bone rather than a primary origin site, though tumors often provoke periosteal reaction as they grow.

Osteosarcoma arises from osteoblasts that lay down osteoid, so it loves places where bone formation is most active. In long bones, the metaphysis is the region just beside the growth plate where remodeling and osteoblastic activity are high and blood supply is abundant. That combination makes it the likeliest origin site for malignant osteoblasts to transform and start growing. Because of this, dogs commonly develop osteosarcoma starting in the metaphysis of weight-bearing long bones (like the distal radius, proximal tibia, distal femur, and proximal humerus). The epiphysis and diaphysis are less typical primary sites, and the periosteum is a tissue around bone rather than a primary origin site, though tumors often provoke periosteal reaction as they grow.