Colon
Carcinoma
Mucinous adenocarcinoma
Author: Raul S. Gonzalez, M.D.
Editorial Board Member: Catherine E. Hagen, M.D.
Editor-in-Chief: Debra L. Zynger, M.D.
Topic Completed: 12 April 2021
Minor changes: 12 April 2021
Copyright: 2002-2021, PathologyOutlines.com, Inc.
PubMed Search: Mucinous carcinoma [title] colon
Table of Contents
Definition / general | Essential features | Terminology | Epidemiology | Sites | Pathophysiology | Clinical features | Prognostic factors | Case reports | Gross description | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Molecular / cytogenetics description | Sample pathology report | Differential diagnosis | Additional references | Board review style question #1 | Board review style answer #1Cite this page: Gonzalez RS. Mucinous adenocarcinoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/colontumorcolloid.html. Accessed July 31st, 2021.
Definition / general
- WHO recognized subtype of colorectal carcinoma with mucin lakes comprising at least 50% of tumor mass, though utility of 50% cutoff is unclear (Histopathology 2019;74:406)
Essential features
- Most common subtype of colorectal carcinoma
- Mucin production easily observed on histology
- Some cases are microsatellite instability (MSI) high
- Unclear whether worse prognosis than conventional colorectal carcinoma
Terminology
- Variably called colloid carcinoma
Epidemiology
- Relatively common (10% of all colorectal carcinomas) (Cancer 1976;37:1891)
- Incidence is stable (Dis Colon Rectum 2005;48:1161)
Sites
- Usually arises in the right colon (J Clin Pathol 2012;65:381)
Pathophysiology
- Associated with microsatellite instability, though most mucinous carcinomas are not MSI high (Cancer 2005;103:2023, Am J Pathol 2001;158:527)
Clinical features
- Typically presents at more advanced stage and with greater nodal involvement than standard colorectal carcinoma (Dis Colon Rectum 1993;36:49, Gastroenterol Hepatol 2002;25:534)
- May recur locally following excision (World J Surg Oncol 2012;10:109)
Prognostic factors
- May have same or worse prognosis compared with standard colorectal carcinoma (Ann Oncol 2012;23:135, J Surg Oncol 2000;73:70)
Case reports
- 11 year old girl with colloid carcinoma of rectum (J Postgrad Med 1993;39:218)
- 77 year old man with large mucinous adenocarcinoma (Dig Surg 2003;20:69)
Gross description
- Exophytic, gelatinous mass
Gross images
Images hosted on other servers:
Causing intussusception
Cecal tumor
Arising in villous adenoma
Microscopic (histologic) description
- Adenocarcinoma with strips of tumor cells floating in large extracellular mucin lakes comprising at least half of tumor mass
- Signet ring cells (with intracellular mucin) may also be present but should comprise less than half of tumor
Microscopic (histologic) images
Contributed by Raul S. Gonzalez, M.D.
Abundant extracellular mucin
Epithelial cells within mucin
Positive stains
- CDX2 (100%)
- MUC2 (100%)
- CK20 (98%)
- Beta catenin (nuclear) (64%)
- CK7 (19%, usually rectal)
- MUC6 (5%)
- Reference: Am J Surg Pathol 2011;35:1830
Molecular / cytogenetics description
- KRAS mutations more common and TP53 mutations less common than in standard colorectal carcinomas (Mod Pathol 2006;19:59)
Sample pathology report
- Ascending colon, resection:
- Mucinous adenocarcinoma, well differentiated (see synoptic report)
Differential diagnosis
- Colitis cystica profunda:
- May form a mass and demonstrate copious extracellular mucin but epithelium is clearly benign
- Signet ring cell carcinoma:
- More than half of tumor composed of signet ring cells
Additional references
Board review style question #1
Which of the following is true about mucinous adenocarcinoma of the colorectum?
- It is the most common subtype of colorectal carcinoma
- It unequivocally has a better prognosis than standard colorectal carcinoma
- It usually affects pediatric patients
- Signet ring cells are always at least a minor component
Board review style answer #1
A. It is the most common subtype of colorectal carcinoma
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Reference: Mucinous adenocarcinoma
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Reference: Mucinous adenocarcinoma
