Cytokeratin 1 (CK1, K1)

Author: Nat Pernick, M.D.

Revised: 15 May 2018, last major update October 2013

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

PubMed Search: ck1[title]
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Cite this page: Pernick, N. Cytokeratin 1 (CK1, K1). website. Accessed January 22nd, 2019.
Definition / general
Uses by pathologists
  • No significant clinical use by pathologists
Positive staining - normal
  • Endothelial cells, skin and other squamous epithelium (suprabasal spinous and granular layers), thymic Hassal’s corpuscle
Positive staining - disease
  • Angiosarcoma (73%), epithelioid hemangioendothelioma (100%), epithelioid sarcoma (70%), hemangioma (often), schwannoma (62%), squamous cell carcinomas-keratinizing, synovial sarcoma (28%), vascular tumors (greater in well versus poorly differentiated tumors)
Additional references