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Updated: Feb 10, 2026

An Efficient Method to Obtain Dedifferentiated Fat Cells
Published on: July 15, 2016
Dedifferentiated retroperitoneal liposarcoma spontaneously occurring in an aged SD rat
Tomoharu Naito1,2, Tsuyoshi Saito1, Tamami Higuchi2,3
1Department of Human Pathology, School of Medicine, Juntendo University, 1-1-19 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Abstract:
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.
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