A case of giant cell osteosarcoma in a scottish fold cat

Abstract

This study describes a case of giant cell osteosarcoma (GCO) located on the right scapulae in a six-year-old neutered male Scottish Fold cat. GCO is a rare tumor in domestic animals.This tumor is also known as giant cell-rich osteosarcoma. Multinucleated giant cells and osteoid islands are observed in GCO.The mass was 4.6x4.4x4.3 cm in size and very firm. Microscopically, fusiform-shaped cells and multinucleated giant cells were observed. There were 4-8 mitotic figures in three random high-power fields (400x). Osteoid islands and necrosis were detected in several areas. In these areas, atypia was observed in the multinucleated giant cells and fusiform-shaped cells. Immunohisto-chemically, vimentin expression was observed in neoplastic cells.No immunoreactivity against actin and cytokeratin was observed in neoplastic cells. Additionally, vimentin expression was detected in the periphery of blood vessels and actin expression in blood vessel smooth muscle cells. As a result ofhistopathological and immunohistochemical find-ings, the mass was determined to be GCO.