Synovial osteochondromatosis and sclerosing osteosarcoma in a cat

The clinical, radiographic and histological features of synovial osteochondromatosis in multiple joints and an unrelated sclerosing osteosarcoma of the left tibia in a cat are reported. Radiographic evaluation showed signs of several nodular radiopacities in both stifles and both shoulders. Pathologic transverse fractures of the left tibia and fibula were also present. A midfemoral amputation of the left hindlimb was performed and treatment consisted of lifelong administration of nonsteroidal anti-inflammatory drugs. Histological evaluation confirmed synovial osteochondromatosis of the left stifle and sclerosing osteosarcoma of the left tibia. This is the first report of a feline patient with bilateral synovial osteochondromatosis that describes the clinical, radiographic and histological aspects of this disease.