Giant cell tumour of bone in a cat

A domestic shorthaired cat had a firm, non-painful swelling of the left antebrachium. Radiographs showed an expansile, multiloculated lesion in the radius. The mass gradually enlarged over the following four and a half months and the animal became completely lame. The histological diagnosis was giant cell tumour of bone; this is a rare neoplasm of bone in veterinary patients. Giant cell tumour of bone should be considered in the differential diagnosis of bone lesions having an expansile, multiloculated radiographic appearance.