Cytokeratin 7 (CK7, K7)

Author: Nat Pernick, M.D.

Revised: 22 May 2018, last major update December 2011

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

PubMed Search: CK7 stain "loattrfree full text"[sb]
Cite this page: Pernick, N. Cytokeratin 7 (CK7, K7). website. Accessed May 25th, 2018.
Definition / general
  • Type II keratin of simple nonkeratinizing epithelia (OMIM 148059); molecular weight 54 kDa
  • Found in breast, lung, ovary and urothelium, but usually NOT in GI or stratified squamous epithelium
Uses by pathologists
Microscopic (histologic) images

Images hosted on Pathout server:

Contributed by
Dr. Semir Vranic,
University of Sarajevo
(Bosnia and Herzegovina)

Ampullary adenocarcinoma

Case of the Week

Prostate: left nephrogenic adenoma

Case of the Week

Urethra: clear cell adenocarcinoma

Case of the Week

Nasal cavity: seromucinous hamartoma

Case of the Week

Liver: hepatocellular
carcinoma, fibrolamellar

Case of the Week

Lung adenocarcinoma: metastatic to ovary

Case of the Week

Melanoma (uterus)

Case of the Week

Cardiac myxoma with glandular differentiation

Case of the Week

Renal cell carcinomas (left to right): papillary solid variant; tubulocystic

Case of the Week

Breast metaplastic carcinoma

Contributed by Leica Microsystems,
(Biosystems Division)

Ureter (normal)
CK7 (RN7) with
intense cytoplasmic

Images hosted on other servers:

Urothelial carcinoma:
with glandular
differentiation (fig 4)

Anal glands (left-fig E) and transitional zone (right, fig 1B) are CK7+

Anal gland carcinoma is CK7+ (fig C)

Bladder: carcinoid and urothelium are CK7+ (fig F)

Bladder/urethra: clear cell adenocarcinoma

Bladder (left to right): plasmacytoid carcinoma, urachal mucinous cystadenocarcinoma

Breast: Left-cylindroma; right-Paget disease

Cervical adenocarcinoma: Left-intestinal type (fig C); right-signet ring type (fig C)

extrahepatic (fig C)
and gallbladder (fig A)

Colonic and lung carcinoma (fig D-F)

Endometrioid adenocarcinoma (fig C)

Kidney: left - chromophobe carcinoma-eosinophilic variant is CK7+ (fig 2C); right - oncocytoma has scattered CK7+ cells (fig 6)

Nasal cavity: inverted papilloma


Ovarian mucinous cystadenoma is CK7+
(5B) but testicular mucinous cystadenoma
(fig 3B) and colonic epithelium (fig 4B)
are negative

Pancreas: ductal adenocarcinoma (fig E)

Penis/scrotum: mucoid cyst (Fig 6)

Images hosted on Flickr:
Missing Image

Nasal cavity:
respiratory epithelial

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