title: Classification of proliferative hepatocellular lesions in harlan sprague-dawley rats chronically exposed to dioxin-like compounds.
abstract: Over the years, the most appropriate classification scheme for nodular proliferative lesions of the hepatocyte has been heavily debated. In the most recent guidelines there appears to be a consensus for classifying these lesions as hepatocellular adenoma, hepatocellular carcinoma, or regenerative hyperplasia. Also, large foci of cellular alteration may appear somewhat nodular. Some nodular hepatocellular lesions from a group of 7 studies of dioxin and dioxin-like compounds conducted by the National Toxicology Program did not readily fit into these categories. Some of these lesions had morphologic features consistent with hyperplasia. However, there was not sufficient morphological or biological evidence to conclude that the entire response was regenerative. In other instances, these lesions had some features resembling adenoma, but contained a prominent component of biliary epithelium and/or oval cells. This component does not appear to be well described in the literature, and while its presence suggested a nodule to be nonneoplastic, this is inconclusive. This paper describes the morphology of these lesions, as well as the diagnostic approach taken in this series of studies.
authors.affiliation: National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA. Hailey@niehs.nih.gov
authors.forename: James R
authors.initials: JR
authors.lastname: Hailey
authors.forename: Nigel J
authors.initials: NJ
authors.lastname: Walker
authors.forename: Donald M
authors.initials: DM
authors.lastname: Sells
authors.forename: Amy E
authors.initials: AE
authors.lastname: Brix
authors.forename: Michael P
authors.initials: MP
authors.lastname: Jokinen
authors.forename: Abraham
authors.initials: A
authors.lastname: Nyska
mesh_terms: D018248:Adenoma, Liver Cell / Q000139:chemically induced / Q000145:classification* / Q000473:pathology; D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000139:chemically induced / Q000145:classification* / Q000473:pathology; D056486:Chemical and Drug Induced Liver Injury; D004147:Dioxins / Q000633:toxicity*; D005260:Female; D006965:Hyperplasia; D008107:Liver Diseases / Q000145:classification* / Q000473:pathology; D008114:Liver Neoplasms, Experimental / Q000139:chemically induced / Q000145:classification* / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D036401:Toxicity Tests, Chronic
chemical_list: D004147:Dioxins