title: Superficial-type adenomas and adenocarcinomas of the colon and rectum: a comparative morphological study.
abstract: OBJECTIVE
  It has been uncertain whether colorectal carcinomas preferentially arise on preexisting adenomas or de novo. However, from a morphological viewpoint, it seems unlikely that pedunculated or exophytic malignant polyps progress to the deeply ulcerated advanced carcinomas usually found clinically.
  
  
  METHODS
  The morphological features of 26 nonpolypoid, superficial-type colorectal tumors (17 adenomas and 9 adenocarcinomas) were compared to clarify the developmental route of colorectal carcinomas.
  
  
  RESULTS
  The adenomas and adenocarcinomas were very similar in size and gross appearance; however, examination of the surface appearances of unsectioned tumors by dissecting microscopy was helpful for distinguishing the two. Histologically, no adenomatous tissue was found in any case of superficial-type adenocarcinoma. Five of the nine adenocarcinomas, even including those of small size, invaded the submucosal layer, and two showed lymph node metastasis.
  
  
  CONCLUSIONS
  These findings suggest that superficial-type adenocarcinomas show rapid growth and aggressive behavior. We suggest that this type of carcinoma may not progress by the adenoma-to-carcinoma pathway but that it may arise from a very small superficial-type adenoma.
authors.affiliation: Department of Surgery, Kanazawa University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Minamoto
authors.forename: K
authors.initials: K
authors.lastname: Sawaguchi
authors.forename: T
authors.initials: T
authors.lastname: Ohta
authors.forename: T
authors.initials: T
authors.lastname: Itoh
authors.forename: M
authors.initials: M
authors.lastname: Mai
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology*; D000236:Adenoma / Q000473:pathology*; D000328:Adult; D000368:Aged; D003110:Colonic Neoplasms / Q000473:pathology*; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D012004:Rectal Neoplasms / Q000473:pathology*