Alternative Name
Immunohistochemistry (IHC)
Test Description
ICOS (Inducible Co-Stimulator, CD278) is a member of the CD28 family that regulates T-cell activity and immune responses. ICOS is primarily expressed on activated CD4+ and CD8+ T-cells. It plays an important role in the diagnosis of T-cell lymphomas of follicular helper T-cell origin, and is useful when combined with multiple markers for follicular helper T-cells.
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)*
88342x1 or 88341x1
Turnaround Time
Global: 48 hours, Tech-Only (stain only): 24 hours
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.