Mismatch Repair by Immunohistochemistry with Reflex to BRAF Mutation Detection with Reflex to MLH1 Promoter Methylation
Also known as: MSI REFLEX
Use
This test is the preferred screening assay for Lynch syndrome (LS) in individuals diagnosed with colorectal cancer. Mismatch repair irregularities identified via immunohistochemistry (IHC) suggest LS, necessitating further targeted germline mismatch repair gene assays for definitive diagnosis. Anomalies in MLH1, as determined by the IHC segment, trigger reflexive tests to BRAF and possibly MLH1 methylation, elucidating tumor origin and potentially indicating therapeutic pathways.
Special Instructions
The test involves multiple steps, contingent on initial IHC findings. Inclusion of a surgical pathology report is necessary. Testing for Lynch syndrome is refined by BRAF mutation detection and MLH1 promoter methylation assessments, which are billed as additional services in response to certain IHC outcomes.
Limitations
Interpretations from the IHC test are supplemented by reflex tests; no single outcome fully illuminates a patient's Lynch syndrome status. BRAF mutations or MLH1 methylation can suggest sporadic tumor origins, yet such findings do not categorically rule out LS. Consideration of this test's results should always be contextualized within patient history and additional clinical data.
New York Approved
Methodology
Immunoassay (IHC)
Biomarkers
LOINC Codes
- 50595-8
- 50322-7
- 50323-5
- 50324-3
- 50328-4
Result Turnaround Time
1-5 days
Related Documents
For more information, please review the documents below
Specimen
Tumor Tissue (FFPE)
Volume
Not provided
Minimum Volume
10 slides
Container
tissue transport kit (ARUP Supply #47808)
Collection Instructions
Formalin fix (10 percent neutral buffered formalin preferred), paraffin embed, transport block or 15 unstained slides in a tissue transport kit, do not oven bake precut slides.
Storage Instructions
Protect paraffin block/slides from excessive heat.
Causes for Rejection
Less than 25% tumor tissue in paraffin block, non-formalin fixative, decalcified specimens.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | Indefinitely |
| Refrigerated | Indefinitely |
| Frozen | Unacceptable |