Hereditary flat adenoma syndrome: A variant of familial adenomatous polyposis?

Henry T. Lynch, Thomas C. Smyrk, Patrice Watson, Stephen J. Lanspa, Patrick M. Lynch, Joseph X. Jenkins, Jon Rouse, Jennifer Cavalieri, Linda Howard, Jane Lynch

Research output: Contribution to journalArticlepeer-review

81 Scopus citations


We describe the clinical and pathologic features in four extended kindreds that are consistent with the hereditary flat adenoma syndrome (HFAS). This colon cancer susceptibility disorder is believed to be inherited as an autosomal dominant. The principal phenotypic marker is multiple colonic adenomas (usually less than 100), with a tendency for proximal location. The majority of these adenomas are flat or slightly raised and plaquelike, as opposed to polypoid. Colon cancers have typically developed in middle age and show no unusual histologic features. There are a variety of extracolonic manifestations, including adenomas and carcinomas of the small bowel and fundic gland polyps. The HFAS is contrasted with hereditary nonpolyposis colorectal cancer and familial adenomatous polyposis (FAP) and shown to be distinct from both in the numbers and distribution of colonic adenomas and the typical age of cancer diagnosis. The clinical implications of these findings are discussed. Given its linkage to the FAP locus on 5q and the phenotypic parallels between HFAS and FAP, we conclude that HFAS is a variant of FAP.

Original languageEnglish (US)
Pages (from-to)411-421
Number of pages11
JournalDiseases of the Colon & Rectum
Issue number5
StatePublished - May 1992


  • Colon cancer
  • Flat adenoma
  • Heredity
  • Heterogeneity
  • Linkage to chromosome 5q

ASJC Scopus subject areas

  • Gastroenterology


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