title: Growth patterns of superficially elevated neoplasia in the large intestine.
abstract: BACKGROUND
  The growth pattern and malignant potential of superficially elevated neoplastic lesions remain controversial. A flat adenoma is classified as a superficially elevated neoplasm that characteristically demonstrates high-grade dysplasia despite its small size. In contrast, a nodule-aggregating (NA) tumor, which consists of multiple small aggregated nodules, can also be classified as superficially elevated neoplasia.
  
  
  METHODS
  In this prospective study, 2720 consecutive patients undergoing total colonoscopy were examined for superficially for elevated lesions. Clinicopathologic characteristics, Ki-ras mutational status, and overexpression of p53 protein were compared in 25 NA tumors and 55 flat adenomas without a central depression (flat tumor).
  
  
  RESULTS
  All flat tumors had a tubular pattern, whereas 21 of 25 NA tumors showed a villotubular or tubulovillous pattern. Ki-ras mutation was observed in 44% of NA tumors but in none of the flat tumors. Overexpression of p53 protein was found in 12% of NA tumors and 7% of flat tumors.
  
  
  CONCLUSIONS
  NA tumors and flat tumors have different clinicopathologic and genetic characteristics, although both types of tumor are classified as superficially elevated lesions.
authors.affiliation: Second Department of Internal Medicine, Showa University School of Medicine, Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kaneko
authors.forename: T
authors.initials: T
authors.lastname: Kurahashi
authors.forename: R
authors.initials: R
authors.lastname: Makino
authors.forename: K
authors.initials: K
authors.lastname: Konishi
authors.forename: K
authors.initials: K
authors.lastname: Mitamura
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics* / Q000473:pathology*; D000368:Aged; D001483:Base Sequence; D001707:Biopsy, Needle; D016009:Chi-Square Distribution; D003110:Colonic Neoplasms / Q000235:genetics* / Q000473:pathology*; D003113:Colonoscopy; D005260:Female; D011905:Genes, ras / Q000235:genetics*; D006128:Growth; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D009367:Neoplasm Staging; D016133:Polymerase Chain Reaction; D011379:Prognosis; D011446:Prospective Studies; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric; D016159:Tumor Suppressor Protein p53 / Q000032:analysis*
chemical_list: D016159:Tumor Suppressor Protein p53