Technical InfoEdit

Staining PatternEdit

Expression in Normal TissuesEdit

  • Colon
  • Umbrella cells in urothelium[1]
  • Merkel cells

Expression in Neoplastic EntitiesEdit

Tumor name % Positive Staining Number of Cases

Intermediate/Uncertain Malignant PotentialEdit
Tumor name % Positive Staining Number of Cases

Tumor name % Positive Staining Number of Cases
Colonic Adenocarcinoma 100%[2] 20/20[2]
Merkel Cell Carcinoma 78%[2] 7/9[2]

Expression in Non-Neoplastic EntitiesEdit

Pertinent NegativesEdit

This antigen is typically NOT expressed by the following entities:

  • Usually negative in lung adenocarcinoma

Practical Uses / PanelsEdit

  • Often used with CK7 to determine the origin of a carcinoma:
    • Typically CK7+/CK20+ carcinomas:
      • Pancreatic origin
      • Ovarian origin (mucinous)
      • Bile duct origin (extrahepatic, including gallbladder)
    • Typically CK7+/CK20- carcinomas:
      • Breast origin
      • Lung origin
      • Bile duct origin (intrahepatic)
      • Endocervical/Endometrial origin
      • Thyroid origin
    • Typically CK7-/CK20+ carcinomas:
      • Colon origin
    • Typically CK7-/CK20- carcinomas:
      • Prostate origin
      • Adrenal cortex origin
  • Can be used to differentiate urothelial carcinoma in situ (cells below the umbrella cells are CK20+) from non-neoplastic urothelium (only the superficial umbrella cells are CK20+ [seen in normal urothelium])[3]

Common PitfallsEdit

Related Links/Other ResourcesEdit


  1. Am J Surg Pathol 2001 Aug;25(8):1074-8.
  2. 2.0 2.1 2.2 2.3 Mod Pathol. 2000 Sep;13(9):962-72.
  3. Appl Immunohistochem Mol Morphol 2006;14:260