Colon tumor
Carcinoma
Metastases to colon

Author: Raul Gonzalez M.D. (see Authors page)

Revised: 1 February 2016, last major update January 2016

Copyright: (c) 2002-2016, PathologyOutlines.com, Inc.

PubMed Search: Metastases [title] colon
Definition / General
  • Secondary involvement of colon by a neoplasm of extracolonic origin
  • Uncommon (for example, occurs in < 2% of breast and lung carcinomas)
Essential Features
  • Metastases more common in small intestine than in colon
  • Primary lesion is often but not always identifiable
  • Most common primaries are stomach, lung, prostate, breast and ovarian carcinomas, and melanoma
Clinical Features
  • Endometrioid adenocarcinoma: if associated with colonic endometriosis, then represents an enigmatic primary rather than a metastasis
  • Leukemia: usually involves right colon and terminal ileum, as polypoid or transmural infiltrates
  • Melanoma: may have long interval between primary lesion and metastases (Dis Colon Rectum 2003;46:441)
  • Prostate: more common to be direct spread/invasion than a metastasis
    • Resections for rectal cancer may rarely contain lymph nodes with metastatic prostate carcinoma
Clinical Images

Images hosted on Other servers:

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Soft tissue mass due to
squamous cell carcinoma
primary of lung

Case Reports
Gross Description
  • Central ulceration extending toward mucosa, but often sparing it
Micro Description
  • Disease usually resembles primary tumor microscopically
  • Metastases may be present along serosal surface or within the wall, but mucosal involvement is uncommon
  • Adjacent / overlying colonic epithelium is not dysplastic
Micro Images

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Metastatic melaonoma
to sigmoid colon

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Poorly differentiated
squamous cell carcinoma
metastatic from lung

Differential Diagnosis
  • Gastrointestinal stromal tumor: metastatic endometrial stromal sarcoma may mimic but is CD10+ and CD117-
  • Primary colorectal carcinoma: precursor lesion may be present; colonic adenocarcinomas are usually CK20+, CDX2+, CK7-