Colon
Carcinoma
Intramucosal carcinoma
Author: Raul S. Gonzalez, M.D.
Last author update: 3 March 2021
Last staff update: 8 March 2021
Copyright: 2002-2024, PathologyOutlines.com, Inc.
PubMed Search: "Intramucosal carcinoma" colon
Table of Contents
Definition / general | Essential features | Terminology | Clinical features | Case reports | Treatment | Clinical images | Gross description | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Sample pathology report | Differential diagnosis | Board review style question #1 | Board review style answer #1Cite this page: Gonzalez RS. Intramucosal carcinoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/colontumorintramucosal.html. Accessed April 26th, 2024.
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
Essential features
- Adenocarcinoma solely within the mucosal layer of the colon
- Usually within a polyp but may occur in flat mucosa in inflammatory bowel disease
- Term typically not used by Western pathologists, who prefer high grade dysplasia
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
- United States Preventive Services Task Force specifically recommends against using the term intramucosal carcinoma for lesions confined to the mucosa (Gastrointest Endosc 2020;92:997)
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
Images hosted on other servers:
Mass in colonoscopy
Subpeduculated polyp
Gross description
- May appear as a flat / ulcerated lesion or arise in a polyp
Gross images
Images hosted on other servers:
Resected intramucosal carcinoma
Microscopic (histologic) 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)
Microscopic (histologic) images
Contributed by Raul S. Gonzalez, M.D.
Intramucosal carcinoma
Images hosted on other servers:
Intramucosal adenocarcinoma
Sample pathology report
- Rectum, mass, biopsy:
- Tubulovillous adenoma with extensive high grade dysplasia (see comment)
- Comment: The findings are compatible with an interpretation as intramucosal carcinoma, though this concept is rarely applied to colorectal lesions. The sample is relatively superficial and an unsampled invasive process cannot be excluded.
Differential diagnosis
- High grade dysplasia:
- Cutoff unclear; see above
Board review style question #1
Which of the following is true about intramucosal carcinoma of the colorectum?
- It only arises within traditional serrated adenomas
- Roughly 10% of cases metastasize to lymph nodes despite early stage
- There are well defined histologic criteria to distinguish it from high grade dysplasia
- Usage of the term differs between Eastern and Western pathologists
Board review style answer #1
D. Usage of the term differs between Eastern and Western pathologists
Comment Here
Reference: Intramucosal carcinoma
Comment Here
Reference: Intramucosal carcinoma
