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HelpTest Code TROP2 Trophoblast Antigen 2 (TROP2) Immunostain, Semi-Quantitative Immunohistochemistry, Manual
Shipping Instructions
Attach the green "Attention Pathology" address label (T498) to the outside of the transport container before putting into the courier mailer.
Necessary Information
A pathology/diagnostic report and a brief history are required.
Specimen Required
Specimen Type: Tissue
Supplies: Pathology Packaging Kit (T554)
Submit:
Formalin-fixed, paraffin-embedded tissue block
OR
3 Unstained glass, "positively charged" slides with 4-microns formalin-fixed, paraffin-embedded tissue
Additional Information: One slide will be stained with hematoxylin and eosin and returned.
Useful For
Identification of breast and urinary cancer, among others
Method Name
Immunohistochemistry (IHC)
Reporting Name
TROP2, SemiQuant IHC, ManualSpecimen Type
SpecialSpecimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Special | Ambient (preferred) | |
| Refrigerated | ||
Reject Due To
| Decalcified paraffin embedded tissue | Reject |
| Wet/frozen tissue | Reject |
| Cytology smears | Reject |
| Nonformalin fixed tissue including alcohol-formalin-acetic acid (AFA), 95% ethanol, PREFER fixatives or zinc formalin | Reject |
| Nonparaffin embedded tissue | Reject |
| Noncharged slides | Reject |
| ProbeOn slides | Reject |
| Snowcoat slides | Reject |
Clinical Information
Trophoblast antigen 2 (TROP2) is overexpressed in many tissues and cancers, including breast and urinary cancer among others. An antibody drug conjugate, sacituzumab govitecan, targets the cell surface protein TROP2. Tumors with high expression of TROP2 are more likely to respond to targeted drug therapy.
Reference Values
An interpretive report will be provided.
Interpretation
Trophoblast antigen 2 is a membrane protein and immunohistochemical positivity is characterized by a membrane pattern of staining. Results are reported as percent positive cells and intensity of staining.
This result should be interpreted in the appropriate clinical context.
Cautions
This test has been validated for non-decalcified paraffin-embedded tissue specimens fixed in 10% neutral buffered formalin at Mayo Clinic in Rochester, Minnesota. Specimens are recommended to be placed in formalin within 1 hour of acquisition and fixed between 6 hours and 72 hours. This assay has not been validated on tissue or cellblocks subjected to alternative fixatives or decalcification.
Age of a cut paraffin section can affect immunoreactivity. Stability thresholds vary widely among published literature and are antigen dependent. Best practice is for paraffin sections to be cut within 6 weeks.
The charge of glass slides can be affected by environmental factors and subsequently may alter slide staining. Sending unsuitable glass slides can result in inconsistent staining due to poor slide surface chemistry.
Best practices for storage of positively charged slides:
-Minimize time slides are stored after being unpackaged
-Limit exposure to high humidity and heat
-Minimize exposure to plastics
Method Description
Immunohistochemistry on sections of paraffin-embedded tissue.(Unpublished Mayo method)
Day(s) Performed
Monday through Friday
Report Available
5 to 7 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
88360
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| TROP2 | TROP2, SemiQuant IHC, Manual | 105178-8 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 621065 | Interpretation | 59465-5 |
| 621624 | Participated in the Interpretation | No LOINC Needed |
| 621625 | Report electronically signed by | 19139-5 |
| 621626 | Material Received | 81178-6 |
| 621627 | Disclaimer | 62364-5 |
| 621628 | Case Number | 80398-1 |