title: Early precursor of mixed endocrine-exocrine tumors of the gastrointestinal tract: histologic and molecular correlations.
abstract: BACKGROUND
  Mixed endocrine-exocrine tumors display histologic features of endocrine and glandular differentiation. Unlike in collision tumors, the two components are thought to arise from a monoclonal precursor. Evidence from molecular testing supports the monoclonal theory and suggests that the exocrine component may give rise to the endocrine component but not vice versa.
  
  
  METHODS
  We report a case of an adenomatous polyp in the large intestine that had groups of endocrine cells arising from the crypt bases of the adenomatous (exocrine) epithelium. To our knowledge, ours is only the second report of an adenomatous polyp in which groups of microcarcinoid endocrine cells were recognized. The histologic findings in our case correlate with the molecular findings described in mixed endocrine-exocrine tumors.
  
  
  CONCLUSIONS
  Our description may represent the primordial stage of a mixed endocrine-exocrine neoplasm.
authors.affiliation: Department of Medicine, University of Minnesota, Minneapolis, MN.
authors.forename: Fateh
authors.initials: F
authors.lastname: Bazerbachi
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Florida, Jacksonville, FL.
authors.forename: Taher R
authors.initials: TR
authors.lastname: Kermanshahi
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Florida, Jacksonville, FL.
authors.forename: Carmela
authors.initials: C
authors.lastname: Monteiro
keywords: Adenomatous polyps; carcinoid tumor; gastrointestinal neoplasms
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