Late-onset fracture-associated osteosarcoma in a cat

An 18-year-old male, castrated Domestic Shorthaired cat was presented with the complaint of acute severe lameness of the left pelvic limb. There was no history of trauma, apart from a distal physeal left femoral fracture that had been repaired 17 years previously. Radiology revealed a displaced distal metaphyseal femoral fracture with marked areas of bone lysis and periosteal proliferations. A pathological fracture due to a bone neoplasia was suspected. An amputation with coxofemoral disarticulation was performed. Histopathology confirmed the tentative diagnosis of appendicular osteo-sarcoma. No postoperative complications were encountered and the cat made a full recovery. This case shows an unusual presentation of a late-onset fracture-associated feline osteosarcoma.