Mismatch Repair by Immunohistochemistry with Reflex to BRAF Mutation Detection with Reflex to MLH1 Promoter Methylation

Casandra

Casandra Test Code AR63699Version 1 (DRAFT)

Performing Lab

Lab ARUP LaboratoriesLab Test ID 2002327CPT Codes 81210, 81288, 88341, 88342

Mismatch Repair by Immunohistochemistry with Reflex to BRAF Mutation Detection with Reflex to MLH1 Promoter Methylation

Also known as: MSI REFLEX

Clinical Use

Order Test

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

Not provided.

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.

Test Details

New York Approved

Methodology

Immunoassay (IHC)

Biomarkers

3 components

Mismatch Repair by IHC • IHCBRAF Mutation Detection • IHCMLH1 Promoter Methylation • RT-PCR

LOINC Codes

Result Codes

50595-8 - Path Interp Spec-Imp
50322-7 - MLH-1 Ag Tiss Ql ImStn
50323-5 - MSH-2 Ag Tiss Ql ImStn
50324-3 - MSH-6 Ag Tiss Ql ImStn
50328-4 - PMS-2 Ag Tiss Ql ImStn

Result Turnaround Time

1-5 days

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.