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Alternative Name
Cytokeratin 5/6
Immunohistochemistry (IHC)
Test Description

D5/16 B4 clone of CK5/6 antibody reacts strongly with cytokeratins 5 and 6. Cytokeratin 5/6 have been found valuable for the distinction between low differentiated squamous cell carcinoma and adenocarcinoma. It labels mesothelioma, and epithelial basal cells in prostate and tonsil. No reactivity with other mesodermally derived tissues, such as muscle and connective tissues, has been observed. Anti-CK 5/6 has also been found useful in the differential diagnosis of atypical proliferations of the breast.

Specimen Requirements
  • A formalin-fixed, paraffin-embedded (FFPE) tissue block is preferred specimen type
  • 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

Tech-Only (stain only): 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.