Wijesundera Kavindra Kumara, Izawa Takeshi, Fujita Daisuke, Denda Yuki, Seto Eiko, Sasai Hiroshi, Kuwamura Mitsuru, Yamate Jyoji
Laboratory of Veterinary Pathology, Division of Veterinary Sciences, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-58 Rinku-oraikita, Izumisano City, Osaka 598-8532, Japan.
J Toxicol Pathol. 2013 Sep;26(3):309-12. doi: 10.1293/tox.26.309. Epub 2013 Oct 15.
A spontaneously occurring subcutaneous mass in the left forelimb of a nine-year-old rabbit (Oryctolagus cuniculus) was examined histopathologically and immunohistochemically. Clinically, edema and hemorrhage were seen around the mass. No connection of the tumor mass to the appendicular skeleton was found. The tumor was arranged in a solid growth pattern and irregular bundles, and neoplastic cells were polygonal to spindle-shape. Osteoid (positive for osteocalcin) and multinucleated giant cells were diffusely or focally seen. Neoplastic cells were positive for vimentin, osterix and Ki-67, indicating the nature of osteoblasts with proliferating activity, but negative for α-smooth muscle actin, desmin or CD204. Based on these findings, a diagnosis of extraskeletal osteosarcoma was made, a very rare tumor both in laboratory and pet rabbits.
对一只9岁家兔（穴兔）左前肢自发出现的皮下肿块进行了组织病理学和免疫组织化学检查。临床上，肿块周围可见水肿和出血。未发现肿瘤块与附属骨骼有连接。肿瘤呈实体生长模式和不规则束状排列，肿瘤细胞呈多边形至梭形。可见弥漫性或局灶性类骨质（骨钙素阳性）和多核巨细胞。肿瘤细胞波形蛋白、osterix和Ki-67呈阳性，表明具有增殖活性的成骨细胞性质，但α-平滑肌肌动蛋白、结蛋白或CD204呈阴性。基于这些发现，诊断为骨外骨肉瘤，这在实验兔和宠物兔中都是非常罕见的肿瘤。
