Stains & CD markers
Cytokeratin 19 (CK19, K19)
Copyright: 2003-2024, PathologyOutlines.com, Inc.
PubMed Search: CK19[title]
Cytokeratin 19 (CK19, K19)
Author: Nat Pernick, M.D.
Last author update: 1 October 2013
Last staff update: 3 August 2023
Copyright: 2003-2024, PathologyOutlines.com, Inc.
PubMed Search: CK19[title]
Table of Contents
Definition / general | Uses by pathologists | Positive staining - normal | Positive staining - not malignant | Positive staining - malignant | Negative stains | Microscopic (histologic) images | Additional referencesCite this page: Pernick N. Cytokeratin 19 (CK19, K19). PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/stainsck19.html. Accessed April 26th, 2024.
Definition / general
- Molecular weight is 40 kDa (smallest cytokeratin)
- Often coexpressed with CK7
- Present in both simple and complex epithelium
- Involved in the organization of myofibers; links contractile apparatus to dystrophin at costameres of striated muscle (also CK8, Mol Biol Cell 2005;16:4280)
- Polymorphisms of CK19 pseudogene are associated with primary biliary cirrhosis (Hepatol Res 2003;25:281)
Uses by pathologists
- Bladder: possible urine screening test for bladder carcinoma (J Egypt Natl Canc Inst 2006;18:82)
- Bone / soft tissue: distinguish chordoma (CK19+) from parachordoma (CK19-, Ann Diagn Pathol 1997;1:3)
- Breast: presence of CK19+ peripheral blood tumor cells or CK19+ fragments is a poor prognostic factor for breast cancer (predicts CNS relapse, Breast Cancer Res 2006;8:R36)
- Liver: distinguish hepatocellular carcinoma (CK19-) from either hepatoid adenocarcinoma metastatic to liver (CK19+, Am J Surg Pathol 2003;27:1302) or cholangiocarcinoma (CK19+, J Gastrointestin Liver Dis 2006;15:9, Am J Clin Pathol 2006;125:519)
- Liver: poor prognostic factor in hepatocellular carcinoma (Histopathology 2006;49:138, Cancer Sci 2003;94:851)
- Lung: poor prognostic factor for non small cell lung carcinoma (Ann N Y Acad Sci 2006;1075:244, Cancer 2006;107:2842)
- Pancreas: poor prognostic factor in pancreatic endocrine neoplasms (Am J Surg Pathol 2004;28:1145, Am J Surg Pathol 2006;30:1588)
- Thyroid: confirm diagnosis of papillary thyroid carcinoma in cytology or equivocal cases (Arch Pathol Lab Med 2003;127:579, Mod Pathol 2006;19:1631); help distinguish follicular variant of papillary thyroid carcinoma (CK19+) from (a) follicular adenoma (CK19-, Endocr Pathol 2006;17:213, Am J Clin Pathol 2006;126:700 but see Am J Clin Pathol 2001;116:696), (b) hyalinizing trabecular adenoma (CK19-, Am J Surg Pathol 2006;30:1269), (c) Grave’s disease (weak / negative CK19, Endocr Pathol 2005;16:63), (d) multinodular goiter with papillary areas (Endocr Pathol 2002;13:207); note that CK19 may stain benign thyroid lesions
- Metastases: RT-PCR detects nodal and marrow metastases in various carcinomas - bladder carcinoma (poorer survival, Clin Cancer Res 2005;11:3773), breast (Anticancer Res 2006;26:3855, Jpn J Clin Oncol 2003;33:167), gastric (World J Gastroenterol 2006;12:5219), head and neck squamous cell (Br J Cancer 2006;94:1164), skin (Br J Dermatol 2003;149:998); note that pelvic lymph nodes may have false positives (Int J Cancer 2007;120:1842)
- Peripheral blood tumor cells: RT-PCR detects peripheral blood tumor cells in carcinoma of cervix (Gynecol Oncol 2002;85:148), colon (Gut 2002;50:530), gallbladder (Rev Med Chil 2004;132:1489), pancreas (World J Gastroenterol 2007;13:257); the significance of these tumor cells is unclear (Ann Oncol 2005;16:1845)
Positive staining - normal
- Anal transition zone (Histopathology 1995;26:39)
- Bile ducts and ductules
- Breast (ductal and secretory cells)
- Colon
- Conjunctiva (Invest Ophthalmol Vis Sci 2006;47:4780)
- GI epithelium
- Hair follicles (J Invest Dermatol 1989;92:707)
- Muscle fibers
- Myoepithelium
- Nipple epidermis
- Pancreatic ducts (Pancreas 2005;30:158)
- Salivary gland acini (Res Commun Mol Pathol Pharmacol 1998;101:115)
- Squamous epithelium (basal layers, BMC Cancer 2006;6:10)
- Sweat glands
- Umbilical cord
- urothelium
Positive staining - not malignant
- Adamantinoma (Pathol Int 2000;50:801)
- Ameloblastoma (stellate reticulum-like areas, Bull Tokyo Dent Coll 2002;43:13)
- Cholesteatoma (Histol Histopathol 2007;22:37)
- Chordoma (references above)
- Hepatoblastoma (embryonal subtype, Pediatr Dev Pathol 2006;9:196)
- Oral dysplasia (Zhonghua Kou Qiang Yi Xue Za Zhi 2002;37:187)
- Posterior polymorphous corneal dystrophy (Exp Eye Res 2007;84:680)
- Pulmonary interstitial pneumonia - hyaline membranes (some, Pathology 2003;35:120)
- Synovial sarcoma (Histopathology 1998;33:501)
- Syringocystadenoma papilliferum of skin (Br J Dermatol 2002;147:936)
Positive staining - malignant
- Anal (Virchows Arch 2001;439:782)
- Breast (Med Mol Morphol 2006;39:8)
- Cholangiocarcinoma (references above)
- Endometrial (Int J Gynecol Pathol 2011;30:484)
- Hepatoid adenocarcinoma (references above)
- Kidney: medullary, mucinous & tubular spindle cell (Virchows Arch 2005;447:978) medullary, papillary, renal cell (collecting duct-Appl Immunohistochem Mol Morphol 2002;10:332), tubulocystic, urothelial (Am J Surg Pathol 2005;29:747)
- Lung (Histopathology 2004;45:125)
- Paget disease (extramammary, Histopathology 2006;48:723)
- Pancreatic ductal (references above)
- Squamous cell (various sites-Histopathology 1993;23:45)
- Thyroid papillary (references above)
Negative stains
- Cornea (Cornea 2003;22:533)
- Hepatocytes (Hepatology 1996;23:476)
- Hepatocellular carcinoma (usually)
- Pancreatic islets
- Parachordoma
- Thyroid hyalinizing trabecular adenoma
- Trichilemmoma (Br J Dermatol 2003;149:99)
Microscopic (histologic) images
Contributed by Andrey Bychkov, M.D., Ph.D.
CK19 expression in PTC
CK19: prominent membranous and cytoplasmic staining
Images hosted on other servers:
Squamous cell carcinoma, oral (fig B)
Stomach: complete intestinal metaplasia
Additional references
