Cytokeratin 20 (CK20, K20)

Author: Kara Hamilton, MS, Nat Pernick, M.D.

Revised: 26 July 2018, last major update July 2013

Copyright: (c) 2003-2018,, Inc.

PubMed Search: CK20 [title]
Cite this page: Hamilton, K., Pernick, N. Cytokeratin 20 (CK20, K20). website. Accessed December 11th, 2018.
Definition / general
  • Epithelial marker (MW 46 kDa) with restricted expression compared to CK7 (OMIM #608218)
Uses by pathologists
Microscopic (histologic) images
Images hosted on Pathout server:

Contributed by
Leica Microsystems
(Biosystems Division)

Colon (normal):
CK20 (PW31) with
intense cytoplasmic

 Contributed by
 Andrey Bychkov, M.D., Ph.D.

Ovarian cancer

Images hosted on other servers:

Anal glands are CK20-
(fig 1C) but rectal
adenocarcinoma is CK20+
(fig 2)

intestinal type
is CK20- (fig 1E)

Colonic adenocarcinoma: #1-well differentiated; #2-poorly differentiated; #3-metastatic; #4-primary (fig G) and metastatic to lung (fig H)

Colonic medullary
carcinoma (fig 4)

Craniopharyngioma is CK20-

Gastric carcinoma
(poorly differentiated
fig A)

Pancreatic ductal carcinoma is CK20-

PanIN lesions: CK20+ in grades 1, 2 and 3

Prostatic adenocarcinoma; #2 with positive staining of verumontanum

Rectal adenocarcinoma (fig 2)

Sinonasal adenocarcinoma: intestinal type (fig 4B)

Testicular mucinous cystadenoma is CK20+

Tubular adenocarcinoma

Urothelial carcinoma: #1-high grade; #2-CK20+ primary and nodal metastasis

Positive staining - normal
Positive staining - not malignant
Positive staining - malignant
Negative staining