Uncommon Mucosal Metastases in Endoscopic Colorectal Biopsies: A 20-year Single-Institution Review of 55,154 Consecutive Endoscopic Colorectal Biopsies

Authors

  • Suresh Tharmaradinam Department of Pathology and Laboratory Medicine, University of Saskatchewan, Royal University Hospital, 103 Hospital Drive, Saskatoon, Saskatchewan, S7N 0W8, Canada
  • Selliah Kanthan Division of General Surgery, University of Saskatchewan, Royal University Hospital, 103 Hospital Drive, Saskatoon, Saskatchewan, S7N 0W8, Canada
  • Dana Diudea Department of Pathology and Laboratory Medicine, University of Saskatchewan, Royal University Hospital, 103 Hospital Drive, Saskatoon, Saskatchewan, S7N 0W8, Canada
  • Rani Kanthan Department of Pathology and Laboratory Medicine, University of Saskatchewan, Royal University Hospital, 103 Hospital Drive, Saskatoon, Saskatchewan, S7N 0W8, Canada

Keywords:

Gastrointestinal Tract Metastases; Endoscopic Biopsies; Non-Colonic Mucosal Lesions; Lineage Specific Immunohistochemistry; Colorectal Mucosal Metastases; Primary Site of Origin

Abstract

Background: Colorectal endoscopic biopsies are the commonest biopsy specimens in surgical pathology
practice with the implementation of screening colonoscopy to detect early colorectal cancer.
Aim: The aim of this study was to examine the frequency of non-colonic mucosal metastases to their
primary site of origin and their identification in endoscopic colorectal biopsies.
Design: Recent identification of four endoscopic biopsies with mucosal metastases from breast, lung,
merkel cell and endometrium resulted in a 20-year computerized data search of biopsies with the
diagnosis of colon/rectum and breast/lung/Merkel/endometrial/prostate/ovary/urothelial/melanoma/
renal/thyroid”. Non-endoscopic biopsies from laparoscopy/laparotomy/autopsy were excluded. Studyselected
cases were reviewed with their original malignancy in the context of clinical history with
review of relevant literature.
Results: 52 cases ~0.4% of non-colonic mucosal metastases were recognized from 13,564 malignant
biopsies of 55,154 colorectal mucosal biopsies. The primary sites of origin identified using
immunohistochemical markers were: Prostate-17 cases~33%, Ovary-12 cases~23%, Breast and
Urothelial-7 each~13%, Lung, Renal, Endometrial-2 each~4%, Merkel Cell Carcinoma, Malignant
Melanoma, Thyroid-1 each~2% ; thus 27% were extra-pelvic in origin. They were predominant in
males (29) than females (23) with equal distribution in colonic and rectal biopsies. The average disease
interval between the original malignancy and endoscopic colorectal metastases was 7yrs.
Conclusions: Although primary colorectal carcinoma is the commonest malignant diagnosis of
colorectal endoscopic biopsies, malignancies from non-colonic organs, though uncommon, can present
as mucosal metastases, often with delayed intervals. Familiarity and awareness of these uncommon
metastases is vital for accurate pathological diagnosis, aided by newer immunohistochemical markers.
Such precise information is critical for judicious triaging in planning further patient management.

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Published

2022-12-01

Issue

In Press

Section

Articles