Pseudo-carcinomatous Invasion in Adenomatous Polyps of the Colon and Rectum T. Muto 1 , H. J. R. Bussey 2 , B. C. Morson 2 1Department of Surgery, University of Tokyo 2Department of Pathology, St. Mark's Hospital pp.641-646
Published Date 1974/5/25
DOI https://doi.org/10.11477/mf.1403111871
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 The histology of pseudo-carcinomatous invasion in adenomatous polyps of the colon and rectum is described and the appearances are contrasted with those seen in malignant polyps. Prominent features of preudo-carcinomatous invasion are summarized as follows: 1) Aadenomatous tubules are found in the submucosal layer in continuity with the neoplastic tissue in the head of the polyp. 2) The submucosal glands are surrounded by lamina propria without any desmoplastic reaction to the epithelial cells. 3) Cystic change is very pronounced in many of the pseudocarcinomatous glands. 4) There are deposits of pigment with the staining characteristics of haemosiderin around the submucosal glands. 5) The gland-like structures are usually surrounded by a narrow rim of granulation tissue composed of collagen and inflammatory cells. 6) There are marked branching and excess of muscularis mucosae in some pseudo-carcinomatous polyps.

 The recognition of pseudo-carcinomatous invasion is important in the differential diagnosis of benign and malignant polyps of the large bowel. Failure to distinguish it from carcinoma may lead to wrong treatment and false reports of the incidence and prognosis of cancer of the colon and rectum.

 The polyps with pseudo-carcinomatous invasion are mostly situated in the sigmoid part of the colon with large size and exceptionally long stalks. The evidence suggest that pseudo-carcinomatous invasion may be the result of repeated twisting of the stalk of a polyp which causes haemorrhage and this facillitates the passage of non-malignant adenomatous epithelium through the muscularis mucosae.

Copyright © 1974, Igaku-Shoin Ltd. All rights reserved.


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