Non-polypoid adenomas of the colon are associated with subjacent lymphoid nodules. An experimental study in rats

Scand J Gastroenterol. 1999 May;34(5):504-8. doi: 10.1080/003655299750026245.


Background: Subjacent lymphoid nodules (SLNs) have been found in 38% of non-polypoid colonic adenomas in humans. In the present work the presence of SLNs in experimentally induced colonic adenomas was investigated in rats.

Methods: 1,2-Dimethylhydrazine was injected subcutaneously in 290 Sprague-Dawley rats for 27 weeks.

Results: An SLN was present in 28.6% of the 84 adenomas, in 8.4% of the 119 adenocarcinomas, and in 9.7% of the 31 small carcinomas without remnant adenomatous tissue. An SLN was found in 35.6% of the 59 non-polypoid neoplasias but only in 9.1% of the 175 polypoid (that is, exophytic) neoplasias. When only adenomas were considered, SLNs were present in 50.0% of the 34 non-polypoid adenomas but only in 14.0% of the 50 polypoid adenomas.

Conclusions: Non-polypoid colonic adenomas evolve preferentially from the minimal fraction of the colonic mucosa that overlays the few existing lymphoid nodules in rats.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenoma / pathology*
  • Animals
  • Colonic Neoplasms / pathology*
  • Female
  • Lymphoid Tissue / pathology*
  • Male
  • Rats
  • Rats, Sprague-Dawley