Fracture-associated sarcoma in the dog.

Seven fracture-associated sarcomas developed in large-breed dogs after stabilization of comminuted long bone fractures with stainless steel plates and screws. In most cases, the healing pattern of the fractures was disturbed. The mean interval between fracture occurrence and tumor diagnosis was 5.5 years. Radiographically, the sarcomas were typified by smooth-bordered subperiosteal proliferation and soft tissue mineralization. Cortical destruction was variable. Several histologic subtypes of osteosarcoma were seen. Four sarcomas had a marked inflammatory cell component and 5 of the dogs had clinical evidence of chronic infection. These findings were similar to those in 35 previously reported fracture-associated sarcomas, even though many types of fixation devices in addition to plates, as well as no fixation at all, were represented in these cases. Fracture-associated sarcomas most frequently were found to be diaphyseal, and the femur accounted for almost half of the sarcomas reported.