OSTEOSSARCOMA FIBROBLÁSTICO DE TÍBIA COM TRATAMENTO DE LIMB-SPARING EM GOLDEN RETRIEVER

Resumo

Background: Appendicular osteosarcoma is the most prevalent primary bone tumor in dogs. Radiographically, it typically exhibits a mixed pattern of osteolysis and osteoproliferation. Characteristic features include lytic and sclerotic lesions affecting all bone layers, periosteal reactions, and increased soft tissue volume surrounding the lesion. These radiographic changes aid in determining the lesion’s extent guide diagnostic and therapeutic decision-making. Limb-sparing surgery, which involves excision of the oncologic compartment and reconstruction using metallic or biological implants, offers outcomes comparable with those of limb amputation combined with chemotherapy.

Case: A 2.5-year-old female Golden Retriever was presented to the Veterinary Hospital of the School of Veterinary Medicine and Animal Science at the Universidade Federal de Goiás (HV/EVZ/UFG) with progressive lameness and swelling in the left stifle region previous 3 months. Radiographic imaging revealed lytic lesions in the left tibia consistent with a bone neoplasm. Specifically, the images demonstrated well-circumscribed zones of bone lysis with defined margins, along with areas exhibiting a “moth-eaten” appearance affecting the epiphysis and metaphysis. Synovial effusion and increased soft tissue volume were also noted. Histopathological and immunohistochemical evaluations confirmed the diagnosis of fibroblastic osteosarcoma. After discussing the available options, the veterinary team and the dog’s guardian opted for limb-sparing surgery. The procedure involved an osteotomy with resection of the tumor-involved segment and joint arthrodesis using a metallic implant. Two months postoperatively, the patient was brought back to hospital with a tibial fracture. Follow-up thoracic radiographs revealed pulmonary metastases. In light of the poor prognosis, euthanasia was recommended and subsequently performed.

Discussion: Accurate interpretation of the diverse radiographic presentations of appendicular osteosarcoma is essential for diagnosis and treatment planning. Although radiographic findings may initially appear purely lytic or sclerotic, a mixed pattern is more typical and should be carefully differentiated from early-stage osteomyelitis. Histopathological and immunohistochemical analyses are often required to determine the histogenesis of poorly differentiated neoplasms, particularly when morphology alone is inconclusive. While limb-sparing surgery is a viable alternative to amputation in selected canine patients with appendicular osteosarcoma, careful case selection is essential to reduce the risk of complications. Advanced imaging modalities are recommended for precise surgical planning and disease staging. Despite the prevalence of appendicular osteosarcoma in dogs, long-term survival remains a significant clinical challenge. In this case, the dog survived for 2 months following surgery before experiencing local recurrence and pulmonary metastasis. Radiographic imaging was instrumental not only in initial diagnosis but also in guiding surgical strategy and monitoring postoperative outcomes. Effective clinical management of osteosarcoma requires a multidisciplinary approach involving veterinary oncologists, surgeons, radiologists and pathologists. A comprehensive, team-based strategy is critical to optimizing therapeutic success and improving survival outcomes in affected patients.