title: Spontaneous carcinosarcoma originating from the renal pelvis ina rat.
abstract: Carcinosarcoma is a rare neoplasm composed of malignant epithelial and stromal elements, and, for rats, carcinosarcomas in the kidney have not been reported. In a long-term study to gather background data, we encountered a spontaneous carcinosarcoma originating from the renal pelvis with metastasis to the lung. At necropsy, a mass was observed in the abdominal cavity, and white nodules were scattered in lung lobes. Microscopically, there was polypoid hyperplasia of the urothelium accompanied by hyperplasia of spindle stromal cells in the pelvis. The intra-abdominal tumor was composed of epithelial and stromal elements; in the lung, the tumor cells invaded along alveoli/bronchi and occasionally invaded the parenchyma from the blood vessels. Immunohistochemical and electron microscopic examinations revealed that the epithelial element consisted of transitional epithelial cells and that the stromal element consisted of lipoblasts. The tumor was diagnosed as a carcinosarcoma originating from the renal pelvis, and this is the first report of a carcinosarcoma originating from the renal pelvis in a rat.
authors: Tsukuba Drug Safety, Global Drug Safety, Biopharmaceutical Assessments Core Function Unit, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba, Ibaraki 300-2635, Japan.
authors: Akira
authors: A
authors: Inomata
authors: Preclinical Safety Research Laboratories, Kawashima Division, Sunplanet Co., Ltd., 1 Kawashimatakehaya-machi, Kakamigahara, Gifu 501-6024, Japan.
authors: Kazuhiro
authors: K
authors: Hayakawa
authors: Preclinical Safety Research Laboratories, Kawashima Division, Sunplanet Co., Ltd., 1 Kawashimatakehaya-machi, Kakamigahara, Gifu 501-6024, Japan.
authors: Toyohiko
authors: T
authors: Aoki
authors: Tsukuba Drug Safety, Global Drug Safety, Biopharmaceutical Assessments Core Function Unit, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba, Ibaraki 300-2635, Japan.
authors: Satoru
authors: S
authors: Hosokawa
keywords: carcinosarcoma; lung; metastasis; renal pelvis; spontaneous