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Alternative Name
Cytokeratin 20
Immunohistochemistry (IHC)
Test Description
Cytokeratin 20 (CK20) positivity is seen in the majority of adenocarcinomas of the colon, mucinous ovarian carcinomas, transitional cell, and Merkel cell carcinomas, and frequently in adenocarcinomas of the stomach, bile system and pancreas. CK7/CK20 immunostaining patterns may be helpful in separating pulmonary from colonic adenocarcinomas.
Specimen Requirements
  • A formalin-fixed, paraffin-embedded (FFPE) tissue block is preferred specimen type
  • or
  • One (1) unbaked, unstained slide for H&E staining (required) and two to three (2-3) positively charged unstained slides (all cut at 4-5 microns) for each test/antibody ordered
  • Block and slide identifiers should be clearly written and match exactly with the specimen ID and specimen labeling as noted on the requisition.
Storage and Transportation
Use cold pack for transport. Make sure cold pack is not in direct contact with specimen.
CPT Code(s)*
88342 x 1 or 88341 x 1
Turnaround Time
24 hours
New York Approved
Level of Service
Stain Only

*The CPT codes provided with our test descriptions are based on AMA guidelines and are for informational purposes only. Correct CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed.