title: Small encapsulated hepatocellular carcinoma of the liver. Provisional analysis of pathogenetic mechanisms.
abstract: BACKGROUND
  Small hepatocellular carcinomas frequently were found incidentally during routine pathologic examinations of adult livers removed at liver transplant.
  
  
  METHODS
  Sixty-nine carcinomas of all sizes were found in 25 patients; 39 of the tumors were smaller than 1 cm in diameter, and 18 of the carcinomas in five patients were not clinically suspected. These small incidental carcinomas lend themselves to analysis of the morphologic basis of human hepatocellular carcinogenesis.
  
  
  RESULTS
  All of these tumors arose in cirrhotic livers. Most of the small carcinomas were multilobulated and subdivided by pre-existing fibrous septa. The surrounding capsule usually was not a true capsule. They were all well differentiated, most formed bile, Mallory bodies, or showed alpha-1-antitrypsin (A1AT) positivity. Transition from cirrhotic nodular parenchyma to areas of hyperplasia or atypical hyperplasia to well-differentiated carcinoma were common. Large cell dysplasia also was common.
  
  
  CONCLUSIONS
  These morphologic transitions closely parallel changes seen in experimental chemical carcinogenesis. They also strongly suggest a multicentric origin of the tumors. In addition, in every instance, the lesions were multiple in the liver and involved both lobes. This latter finding has possible implications for recurrence after local surgical excision of small hepatocellular carcinomas.
authors.affiliation: Department of Pathology, Toronto Hospital, Ontario, Canada.
authors.forename: R G
authors.initials: RG
authors.lastname: Cameron
authors.forename: P D
authors.initials: PD
authors.lastname: Greig
authors.forename: E
authors.initials: E
authors.lastname: Farber
authors.forename: S
authors.initials: S
authors.lastname: Wilson
authors.forename: M
authors.initials: M
authors.lastname: Sherman
authors.forename: G A
authors.initials: GA
authors.lastname: Levy
authors.forename: M J
authors.initials: MJ
authors.lastname: Phillips
mesh_terms: D000328:Adult; D006528:Carcinoma, Hepatocellular / Q000209:etiology* / Q000473:pathology*; D002471:Cell Transformation, Neoplastic / Q000473:pathology; D006801:Humans; D008113:Liver Neoplasms / Q000209:etiology* / Q000473:pathology*