title: Hepatocellular adenoma with severe fatty change in a male Spontaneously Diabetic Torii rat.
abstract: The Spontaneously Diabetic Torii (SDT) rat is a rat model of nonobese type 2 diabetes mellitus, and hepatocellular adenomas have not been reported in this model. We report a hepatocellular adenoma with severe fatty change in a male 42-week-old SDT rat fed a high-fat diet. At necropsy, the animal had a whitish nodular mass of approximately 2 cm in diameter in the right medial lobe. Histologically, the mass was well demarcated from the surrounding tissues, slightly compressing the adjacent hepatic parenchyma and widely compartmented by fibrous connective tissues. The mass consisted of vacuolated tumor cells resembling hepatocytes with a solid and occasionally trabecular growth pattern. Abundant neutral lipids, which were positive for fat with Oil Red O stain and which ultrastructurally had moderately dense material, were contained within the vacuoles of the tumor cells. Immunohistochemically, the tumor cells showed an increase in immunoreactivity or number for Cytokeratin 8/18 and proliferating cell nuclear antigen but were negative for mesenchymal markers. From these findings, the mass could be distinguished from hepatocellular hyperplasia and was diagnosed as hepatocellular adenoma. In rats, hepatocellular adenoma accompanied by severe fatty change is rare, and this is the first report of a hepatocellular tumor with severe fatty change in a SDT rat.
authors.affiliation: Toxicology Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 23 Naganuki, Hadano, Kanagawa 257-0024, Japan.
authors.forename: Eriko
authors.initials: E
authors.lastname: Taniai-Riya
authors.affiliation: Toxicology Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 23 Naganuki, Hadano, Kanagawa 257-0024, Japan.
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Miyajima
authors.affiliation: Toxicology Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 23 Naganuki, Hadano, Kanagawa 257-0024, Japan.
authors.forename: Kochi
authors.initials: K
authors.lastname: Kakimoto
authors.affiliation: Biological/Pharmacological Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc.,1-1 Murasaki-cho, Takatsuki, Osaka 569-1125, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ohta
authors.affiliation: Toxicology Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 23 Naganuki, Hadano, Kanagawa 257-0024, Japan.
authors.forename: Yuzo
authors.initials: Y
authors.lastname: Yasui
authors.affiliation: Toxicology Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 23 Naganuki, Hadano, Kanagawa 257-0024, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kemmochi
authors.affiliation: Toxicology Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 23 Naganuki, Hadano, Kanagawa 257-0024, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Anagawa-Nakamura
authors.affiliation: Toxicology Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 23 Naganuki, Hadano, Kanagawa 257-0024, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Toyoda
authors.affiliation: Toxicology Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 23 Naganuki, Hadano, Kanagawa 257-0024, Japan.
authors.forename: Akemi
authors.initials: A
authors.lastname: Takahashi
authors.affiliation: Toxicology Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 23 Naganuki, Hadano, Kanagawa 257-0024, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Shoda
keywords: Spontaneously Diabetic Torii rat; fatty change; hepatocellular adenoma; liver; microscopic finding