Mismatch Repair by Immunohistochemistry
Ordering Recommendation

First-line screening test for Lynch syndrome. Highly recommended prior to ordering germline mismatch repair mutation analysis gene testing. Directs subsequent genetic diagnostic testing for Lynch syndrome.   

Qualitative Immunohistochemistry
Within 5 days
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
ARUP Consult®
Disease Topics
Specimen Required
Patient Preparation
Tumor tissue. 
Specimen Preparation
Formalin fix (10 percent neutral buffered formalin is preferred) and paraffin embed specimen. If sending precut slides, do not oven bake. Transport tissue block or 10 unstained (3-5 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: 5 slides). Protect paraffin block and/or slides from excessive heat. 
Storage/Transport Temperature
Room temperature or refrigerated. Ship in cooled container during summer months. 
Unacceptable Conditions
Frozen specimens. Specimens fixed or processed in alternative fixatives (alcohol, Prefer) or heavy metal fixatives (B-4 or B-5). Depleted or no tumor in tissue. Specimens submitted with non-representative tissue type. 
Only tissue that is clearly carcinoma (established by histological criteria) should be tested. 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. 
Ambient: Indefinitely; Refrigerated: Indefinitely; Frozen: Unacceptable 
Reference Interval
Interpretive Data
Refer to report

Statement B: Compliance Statement B: For laboratory developed tests not using a RUO kit, and for FDA approved, cleared or 510(k) exempt assays with alterations. This test was developed and its performance characteristics determined by ARUP Laboratories. The U. S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.

Hotline History
View Hotline History
Component Test Code*Component Chart NameLOINC
0049199Client Case or Ref #49581-2
0049303Mismatch Repair by IHC, Result50595-8
0049305Mismatch Repair by IHC with MLH150322-7
0049310Mismatch Repair by IHC with MSH250323-5
0049320Mismatch Repair by IHC with MSH650324-3
0049325Mismatch Repair by IHC with PMS250328-4
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please view this test within the Laboratory Test Directory found at www.aruplab.com
  • MLH1 IHC
  • MMR Immunostaining
  • MSH2 IHC
  • MSH6 IHC
  • MSI
  • MSI Antibody Immunostaining
  • PMS2 IHC