Stains & CD markers
Cytokeratin 18 (CK18, K18)
Copyright: 2003-2025, PathologyOutlines.com, Inc.
PubMed Search: CK18[title]
Cytokeratin 18 (CK18, K18)
Author: Nat Pernick, M.D.
Last author update: 1 October 2013
Last staff update: 25 June 2021
Copyright: 2003-2025, PathologyOutlines.com, Inc.
PubMed Search: CK18[title]
Table of Contents
Definition / general | Uses by pathologists | Positive staining - normal | Positive staining - not malignant | Positive staining - malignant | Negative staining | Microscopic (histologic) images | Additional referencesCite this page: Pernick N. Cytokeratin 18 (CK18, K18). PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/stainsCK18.html. Accessed April 3rd, 2025.
Definition / general
- Molecular weight is 45 kDa
- Pairs with CK8
- Ethanol causes CK8/18+ Mallory body like inclusions by (a) causing oxidative stress, which (b) inhibits proteasomes that normally remove ubiquinated cytokeratins, which (c) causes accumulation of ubiquinated cytokeratins (Exp Mol Pathol 2006;81:191)
- Various CK8/CK18 mutations may increase susceptibility to liver disease (Gastroenterology 2005;129:885) including cryptogenic cirrhosis (J Clin Invest 1997;99:19)
- Is a marker of fetal mid-face (primary palate) growth and fusion (J Dent Res 2005;84:69)
- Interacts with enteropathogenic E. coli secreted protein F (EspF) and is redistributed after infection (Cell Microbiol 2004;6:987)
- In Chagas’ disease, FLY domain on surface of trypomastigotes binds to CK18, promotes its reorganization and causes increase in number of parasites/cell (Exp Cell Res 2007;313:210, J Biol Chem 2001;276:19382)
- Interacts strongly with HPV16 E1=E4 protein (J Virol 2004;78:821)
Uses by pathologists
- Serum tumor marker for breast cancer (Am J Clin Pathol 2005;123:66) and T3/T4 bladder carcinoma (Clin Biochem 2002;35:327)
- An airway epithelial cell autoantigen associated with nonallergic asthma; a possible serum marker (also CK19) for toluene diisocyanate-induced asthma among exposed workers (Yonsei Med J 2006;47:773)
- RT-PCR to assess sentinel lymph nodes in colon carcinoma (Scand J Gastroenterol 2006;41:1073) and lymph nodes of gastric carcinoma (World J Gastroenterol 2005;11:6530)
- Loss of expression in breast carcinoma may be a poor prognostic factor (Clin Cancer Res 2004;10:2670)
- Cleaved cytokeratin-18 is a marker of apoptosis (J Histochem Cytochem 2005;53:229)
Positive staining - normal
- Simple (i.e. non stratified) epithelial cells
- Eccrine glands (J Cutan Pathol 2007;34:226)
- Endothelium of veins
- Venules and lymphatics (Hum Pathol 2000;31:1062)
- Trophoblast (Arch Pathol Lab Med 2002;126:1480)
Positive staining - not malignant
- Ameloblastoma-peripheral (Oral Diseases-OnlineEarly Articles)
- Breast (references above)
- Chordoma (56%, Mod Pathol 1997;10:545)
- Endothelium of synovial tissue with rheumatic disease (Br J Rheumatol 1993;32:676)
- Epithelioid hemangioendothelioma (100%) and angiosarcoma (epithelioid-50%, nonepithelioid-20%, Hum Pathol 2000;31:1062)
- Hepatoblastoma (epithelial areas, Pediatr Dev Pathol 2006;9:196)
- Hepatoid adenocarcinoma (Am J Surg Pathol 2003;27:1302)
- Inflammatory myofibroblastic tumor (Am J Surg Pathol 2006;30:1502)
- Mallory bodies (J Cell Biol 2005;171:931)
- Papillary tumor of pineal region (J Neuropathol Exp Neurol 2006;65:1004)
- Urothelial metaplasia (Int J Gynecol Pathol 1999;18:125)
Positive staining - malignant
- Adenocarcinoma (various)
- Gastric (Hum Pathol 2004;35:576)
- Hepatocellular (including imprints in 83%, Acta Cytol 2007;51:61)
- Large cell neuroendocrine carcinoma (Am J Clin Pathol 2006;125:682)
Negative staining
- Squamous cell carcinoma (Histopathology 1993;23:45)
Microscopic (histologic) images
Contributed by Leica Microsystems (Biosystems Division)
Colon (normal)
Images hosted on other servers:
Choroid plexus papilloma
Additional references
