Colon
Carcinoma
Medullary carcinoma
Author: Raul S. Gonzalez, M.D.
Last author update: 1 February 2021
Last staff update: 21 June 2024
Copyright: 2002-2024, PathologyOutlines.com, Inc.
PubMed Search: Medullary carcinoma colon
Table of Contents
Definition / general | Essential features | Terminology | Epidemiology | Sites | Case reports | Treatment | Gross description | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Molecular / cytogenetics description | Sample pathology report | Differential diagnosis | Additional references | Board review style question #1 | Board review style answer #1 | Board review style question #2 | Board review style answer #2Cite this page: Gonzalez RS. Medullary carcinoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/colontumormedullary.html. Accessed December 29th, 2024.
Definition / general
- WHO recognized subtype of colon carcinoma with solid growth pattern (Hum Pathol 1999;30:843)
- Relatively rare; usually quoted as < 1% of colorectal neoplasms (Int J Oncol 2010;37:901)
Essential features
- Strongly associated with high degree of microsatellite instability (MSI), indicative of loss of normal DNA repair gene function
- Often better clinical outcome independent of stage than microsatellite stable tumors or tumors with low levels of microsatellite instability
- Usually no / few nodal metastases
Terminology
- Older names: undifferentiated carcinoma, solid type poorly differentiated carcinoma, large cell minimally differentiated carcinoma
Epidemiology
- Often elderly women (average age ~70 years)
Sites
- Usually right sided
Case reports
- 79 year old woman with black, ulcerated cecal tumor (Arch Pathol Lab Med 2005;129:113)
Treatment
- Surgery and chemotherapy (although 5-FU not effective, as with other MSI high tumors)
Gross description
- Large, ulcerating colon mass
Gross images
Images hosted on other servers:
Fleshy, ulcerated lesion
Microscopic (histologic) description
- Malignant, well circumscribed neoplasm with solid growth pattern (no gland formation) and pushing border
- Can form nested, organoid or trabecular patterns
- Cells are uniform, polygonal to round and medium sized with amphophilic cytoplasm, vesicular nuclei with prominent nucleoli and frequent mitotic activity
- Mucin production absent or very focal
- Prominent lymphocytic infiltration within and around tumor
Microscopic (histologic) images
Contributed by Raul S. Gonzalez, M.D.
Medullary carcinoma
Positive stains
Negative stains
- MLH1 and PMS2; neuroendocrine markers (Mod Pathol 2002;15:741)
- CDX2 (positive in 19%), CK7 (positive in 13%), CK20 (positive in 44%) (Hum Pathol 2009;40:398)
Molecular / cytogenetics description
- Associated with microsatellite instability; therefore may be sporadic or arise in Lynch syndrome
- BRAF mutations common (Ann Surg Oncol 2015;22:2988)
- KRAS mutations uncommon (Am J Pathol 2001;159:2239)
Sample pathology report
- Cecum, biopsy:
- Poorly differentiated carcinoma, consistent with medullary carcinoma (see comment)
- Comment: Immunohistochemical stains for MLH1 and PMS2 show aberrant loss of nuclear expression in the tumor. Staining for MSH2 and MSH6 is unremarkable (i.e. retained).
Differential diagnosis
- Lymphoepithelioma-like carcinoma:
- Very rare in colon
- EBER+
- Neuroendocrine carcinoma:
- Positive for neuroendocrine markers (Am J Clin Pathol 2005;123:56)
Additional references
Board review style question #1
Which of the following is typically considered a main pathogenetic aspect of medullary carcinoma of the colon?
- EBV infection
- Microsatellite instability
- POLD1 or POLE mutations
- SWI / SNF complex mutations
Board review style answer #1
Board review style question #2
Which of the following is true about medullary carcinoma of the colon?
- It accounts for 20% of colorectal carcinomas
- It is poorly differentiated, with a poor prognosis
- It most often arises in elderly women
- It usually arises in the rectosigmoid
Board review style answer #2
