Colon tumor
Medullary carcinoma

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

Revised: 4 November 2015, last major update November 2015

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

PubMed Search: Medullary carcinoma [title] colon
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
  • Older names: undifferentiated carcinoma, solid type poorly differentiated carcinoma, large cell minimally differentiated carcinoma
  • Often elderly women (average age ~70 years)
  • Usually right sided
Case Reports
  • Surgery and chemotherapy (although 5-FU not effective, as with other MSI-high tumors)
Gross Description
  • Large, ulcerating colon mass
Gross Images
Missing Image

Fleshy, ulcerated lesion

Micro 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
Micro Images
Missing Image


Missing Image

Solid growth pattern

Missing Image

Medullary (A)

Missing Image

MLH1-, CDX2-

Missing Image

High grade tumor cells,
syncytial pattern

Missing Image


Positive Stains
Negative Stains
Molecular / Cytogenetics Description
Differential Diagnosis
Additional References