Methodology
Immunohistochemistry (IHC)
Test Description
p21 is a cyclin dependent protein kinase inhibitor and is a member of a family of proteins that functions to slow down cell division. p21 is found in t cells as they transitions from G1 phase to S phase. Low nuclear expression of p21 has been associated with poor prognosis in colon and prostate carcinomas.
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 (qualitative IHC) or 88360 x 1 (quantitative/semi-quantitative – manual) or 88361 x 1 (quantitative/semi-quantitative – computer assisted)
Turnaround Time
Global: 48 hours, Tech-Only (stain only): 24 hours
Level of Service
Global
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.