Dedifferentiated retroperitoneal liposarcoma spontaneously occurring in an aged SD rat

作者：Naito Tomoharu; Saito Tsuyoshi; Higuchi Tamami; Inomata Akira; Hayashi Takuo; Shimada Yasuhiro; Yamauchi Ohguchi Atsuko; Kenmochi Sayaka; Kakinuma Chihaya; Yao Takashi

来源：Journal of Toxicologic Pathology, 2018, 31(2): 141-146.

DOI：10.1293/tox.2017-0055

• liposarcoma
• lipoblasts
• SD rat
• spontaneous

Liposarcoma is a rare neoplasm in rats and is characterized by the presence of lipoblasts containing multiple cytoplasmic vacuoles. We encountered a rare type of liposarcoma in a male SD (Crj:CD(SD) IGS) rat during a long-term study to gather background data. At necropsy at 105 weeks of age, there was a large amount of fatty tissue covering the mesentery, pancreas, and retroperitoneum; a white nodule in the right kidney; and paleness of the liver. Microscopically, the tumor had a well-differentiated component and dedifferentiated high-grade component. Immunohistochemical and electron microscopic examinations revealed that the pleomorphic tumor cells retained the characteristics of lipoblasts. Distant or disseminated metastasis was also confirmed in various organs. A liposarcoma with these histological features is extremely rare in rats, and this is the first report of a highly metastatic dedifferentiated type of liposarcoma originating from the abdominal fat tissue in a rat.

• 出版日期2018