Case report 673: Telangiectic osteogenic sarcoma.

A case is presented of a telangiectatic osteogenic sarcoma involving the left third metatarsal of a 4-year-old male Great Dane dog. Radiographs revealed a diaphyseal, expanding, lytic lesion with minimal intralesional sclerosis and a sclerotic rim in the proximal portion. The lesion contained a large amount of blood. The biopsy specimens consisted of spaces which were outlined by fibrous osteoid or granulation tissue. There were islands of multinuclear giant cells and/or fibrous osteoid tissue. A diagnosis of aneurysmal bone cyst was made. The lesion was treated by curettage and insertion of cancellous bone graft but was progressive 10 weeks after treatment. The lesion was further curetted, and these biopsy specimens consisted of aneurysmally dilated spaces and areas of anaplastic sarcomatous cells with mitotic figures and osteoid production, characteristic of telangiectatic osteogenic sarcoma. The dog was euthanized as the owner requested; an autopsy was not performed.