A tumor spontaneously appeared in the left shoulder joint of a 5.5-year-old male Japanese monkey being bred in the laboratory of Matsumoto Dental College, and it grew to be huge. The tumor was removed and examined by light and electron microscopy. The tumor measured up to 15×17×23cm in size and 1,870g in weight. Light microscopic examination indicated that the parenchyma consisted mainly of spindle cells and round cells and some multinucleated giant cells. These cells showed extreme atypia but no cell nests. Some of them had oil-red O positive granules. Electron microscopic observation revealed the granules without limiting membrane in the cytoplasm. Therefore, this case was diagnosed as a poorly differentiated pleomorphic liposarcoma.
本学動物舎において飼育中のサルに自然発生した巨大な悪性腫瘍の1例
