Cytokeratin 8 (CK8, K8)

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Stains & CD markers
Cytokeratin 8 (CK8, K8)

Author: Nat Pernick, M.D.

Last author update: 1 October 2013

Last staff update: 25 June 2021

Copyright: 2003-2024, PathologyOutlines.com, Inc.

PubMed Search: CK8[title]

Table of Contents

Cite this page: Pernick N. Cytokeratin 8 (CK8, K8). PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/stainsck8.html. Accessed December 21st, 2024.

Definition / general

Low molecular weight keratin (52.5-53.5 kDa)
Usually paired with cytokeratin 18
Component of nuclear inclusions of rhabdoid tumors (composed of tangled CK8 and vimentin) and Mallory bodies
Mutated in malignant rhabdoid tumor (Mod Pathol 2002;15:146), chronic pancreatitis (9%, Dig Liver Dis 2003;35:416), liver disease (Proc Natl Acad Sci U S A 2003;100:6063)
May protect hepatocytes from oxidative stress
Cleaved by Chlamydia during infection to permit vacuole expansion necessary for replication (Infect Immun 2004;72:3863)

Uses by pathologists

Confirm epithelial nature of tissue / tumors
Assess sentinel lymph nodes in colon carcinoma (Scand J Gastroenterol 2006;41:1073)

Positive staining - normal

Gallbladder
Intestine
Liver (hepatocytes and bile ductules)
Pancreas
Prostate (basal cells and secretory cells)
Simple type (single layer) epithelium including breast ducts (luminal cells)

Positive staining - not malignant

Ameloblastoma (stellate reticulum-like areas, Oral Dis 1999;5:111)
Autoimmune hepatitis (90%, Acta Cytol 2007;51:61)
Mallory bodies (J Cell Biol 2005;171:931)
Rhabdoid tumor (references above)

Positive staining - malignant

Bile duct
Breast (invasive ductal and DCIS)
Hepatocellular
Neuroendocrine
Pancreatic
Prostate
Renal cell
Squamous cell (cervix-57%, Hum Pathol 2004;35:546; oral cancers-62% from smears, Eur J Cancer B Oral Oncol 1994;30B:405)
Stomach (97%, Hum Pathol 2004;35:576)

Negative staining