Mismatch Repair by Immunohistochemistry with Reflex to BRAF Codon 600 Mutation and MLH1 Promoter Methylation
Preferred screening test for Lynch syndrome (LS) in individuals with colorectal cancer. Definitive diagnosis of LS requires additional targeted germline mismatch repair gene testing. Do not use in endometrial cancer.
Qualitative Immunohistochemistry/Qualitative Real-time Polymerase Chain Reaction
Within 5 days. Within 15 days if reflexed.
New York DOH Approval Status
Tumor Tissue: Formalin fix (10 percent neutral buffered formalin is preferred) and paraffin embed tissue. If sending precut slides, do not oven bake. Transport tissue block or 15 unstained (3- to 5-micron thick sections), positively charged slides in a tissue transport kit (ARUP Supply #47808). Available online through eSupply using ARUP Connect™ or contact ARUP Client Services at (800) 522-2787. (Min: 10 slides). Protect paraffin block and/or slides from excessive heat.
Room temperature. Also acceptable: Refrigerated. Ship in cooled container during summer months.
Less than 25 percent tumor. Specimens fixed/processed in alternative fixatives (alcohol, Prefer). Decalcified specimens.
Include surgical pathology report. Submit electronic request. If you do not have electronic ordering capability, use an ARUP requisition form complete with an ARUP client number. For additional technical details, please contact ARUP Client Services at (800) 522-2787.
If multiple specimens (blocks or slides) are sent to ARUP, they must be accompanied by one of the following: an order comment indicating that the ARUP pathologist should choose the specimen most appropriate for testing (e.g., "Choose best block"), or individual orders for each sample submitted. A Pathologist Block Selection Fee (ARUP test code 3002076) will be added to orders that utilize the first option. If multiple specimens are sent to ARUP without a request for pathologist block/slide selection or individual orders, they will be held until clarification is provided.
Ambient: Indefinitely; Refrigerated: Indefinitely; Frozen: Unacceptable
Refer to report.
Refer to the Colorectal Cancer or Lynch Syndrome topic at arupconsult.com.
This test was developed and its performance characteristics determined by ARUP Laboratories. It has not been cleared or approved by the US Food and Drug Administration. This test was performed in a CLIA certified laboratory and is intended for clinical purposes.
If MLH1 is abnormal for Mismatch Repair by IHC, then BRAF codon 600 will be added. If BRAF codon 600 is negative, MLH1 Promoter Methylation will be added. Additional charges apply.
88342; 88341 x3; if reflexed, add 88381, 81210; if further reflexed, add 81288
|Component Test Code*||Component Chart Name||LOINC|
|0049199||Client Case or Ref #||49581-2|
|0049303||Mismatch Repair by IHC, Result||50595-8|
|0049305||Mismatch Repair by IHC with MLH1||50322-7|
|0049310||Mismatch Repair by IHC with MSH2||50323-5|
|0049320||Mismatch Repair by IHC with MSH6||50324-3|
|0049325||Mismatch Repair by IHC with PMS2||50328-4|
|3002969||MSI Tissue Source|
- MSI reflex to BRAF and MLH1 Methylation
- MSI with BRAF, MLH1reflex