title: Spontaneous Extraskeletal Osteosarcoma in a Rabbit (Oryctolagus cuniculus): Histopathological and Immunohistochemical Findings.
abstract: 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.
authors.affiliation: 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.
authors.forename: Kavindra Kumara
authors.initials: KK
authors.lastname: Wijesundera
authors.forename: Takeshi
authors.initials: T
authors.lastname: Izawa
authors.forename: Daisuke
authors.initials: D
authors.lastname: Fujita
authors.forename: Yuki
authors.initials: Y
authors.lastname: Denda
authors.forename: Eiko
authors.initials: E
authors.lastname: Seto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sasai
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Kuwamura
authors.forename: Jyoji
authors.initials: J
authors.lastname: Yamate
keywords: extraskeletal osteosarcoma; immunohistochemistry; rabbit; spontaneous tumor