Colon tumor
Intramucosal carcinoma of colon

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

Revised: 24 September 2015, last major update September 2015

Copyright: (c) 2002-2015,, Inc.

PubMed Search: Intramucosal carcinoma [title] colon
Definition / General
  • Malignant change confined to mucosa (considered pTis in AJCC staging)
  • Proper cutoff between high grade dysplasia and intramucosal carcinoma is not entirely clear
  • Terminology
  • Controversial term that reflects differing thresholds for malignancy between the West (higher threshold) and Japan (lower threshold), as Japanese pathologists often diagnose as malignant what Western pathologists might call high grade dysplasia
  • Clinical Features
  • Up to 2% of cases may metastasize to lymph nodes (J Clin Oncol 2010;28:e469); earlier theory that colonic mucosa has no lymphatic channels may be erroneous (Histopathology 2015;67:167)
  • Intramucosal carcinoma on biopsy may portend unsampled invasive disease (Ann Surg Oncol 2009;16:3267)
  • Case Reports
  • 51 year old man with sporadic juvenile polyp of the colon harboring an intramucosal adenocarcinoma (Int J Surg Pathol 2015;23:571)
  • 71 year old man with TisN0M1 sigmoid colon cancer (Ann Coloproctol 2014;30:141)
  • Treatment
  • Polypectomy should be sufficient for "intramucosal carcinoma" confined to a polyp, even with a poorly differentiated component (Am J Surg Pathol 2007;31:1882)
  • Endoscopic mucosal resection may be curative (J Gastroenterol Hepatol 2011;26:1619)
  • Clinical Images
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    Mass in colonoscopy

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    Subpeduculated polyp

    Gross Description
  • May appear as a flat / ulcerated lesion or arise in a polyp
  • Gross Images
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    Resected intramucosal carcinoma

    Micro Description
  • Glandular proliferation showing high grade nuclei and architectural complexity, extending no deeper than the muscularis mucosae
  • Necrosis, desmoplasia, and single malignant cells may suggest intramucosal carcinoma over high-grade dysplasia, but this remains subjective
  • Often arises in an adenoma, but may occur in flat colonic mucosa (such as in patients with inflammatory bowel disease)
  • May rarely show signet ring cells (Virchows Arch 2009;454:115)
  • Micro Images
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    Various images

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    Intramucosal adenocarcinoma

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    Inverted hyperplastic polyp

    Differential Diagnosis
  • High grade dysplasia: cutoff unclear; see above