Colon
Carcinoma
Medullary carcinoma


Topic Completed: 1 February 2021

Minor changes: 1 February 2021

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PubMed Search: Medullary carcinoma [title] colon

Raul S. Gonzalez, M.D.
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Cite this page: Gonzalez RS. Medullary carcinoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/colontumormedullary.html. Accessed May 12th, 2021.
Definition / general
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
Treatment
  • Surgery and chemotherapy (although 5-FU not effective, as with other MSI high tumors)
Gross description
  • Large, ulcerating colon mass
Gross images

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Missing Image

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
Molecular / cytogenetics description
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
Board review style question #1

Which of the following is typically considered a main pathogenetic aspect of medullary carcinoma of the colon?

  1. EBV infection
  2. Microsatellite instability
  3. POLD1 or POLE mutations
  4. SWI / SNF complex mutations
Board review style answer #1
B. Microsatellite instability

Comment Here

Reference: Medullary carcinoma
Board review style question #2

Which of the following is true about medullary carcinoma of the colon?

  1. It accounts for 20% of colorectal carcinomas
  2. It is poorly differentiated, with a poor prognosis
  3. It most often arises in elderly women
  4. It usually arises in the rectosigmoid
Board review style answer #2
C. It most often arises in elderly women

Comment Here

Reference: Medullary carcinoma
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