Mismatch Repair by Immunohistochemistry with Reflex to MLH1 Promoter Methylation
Ordering Recommendation

Preferred reflex screening test for Lynch syndrome in non-colorectal cancer tumors (eg, endometrial carcinoma) .

Qualitative Immunohistochemistry/Qualitative Real-time Polymerase Chain Reaction
Within 5 days
If the test reflexes, results will be available within 15 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 tissue. If sending precut slides, do not oven bake. Transport tissue block or 15 unstained (3-5 micron thick sections), positively charged slides in a tissue transport kit (ARUP supply #47808). Available online through eSupply using ARUP ConnectTM or contact ARUP Client Services at (800) 522-2787. (Min: 7 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
Less than 25 percent tumor. Specimens fixed or processed in alternative fixatives (alcohol, Prefer) or heavy metal fixatives (B-4 or B-5). Depleted or no tumor in tissue. 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, 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.

If MLH1 is abnormal for Mismatch Repair by IHC, then MLH1 Promoter Methylation will be added. Additional charges apply.
Hotline History
View Hotline History
CPT Code(s)
88342; 88341 x3; if reflexed, add 81288; 88381
Component Test Code*Component Chart NameLOINC
0049199Client Case or Ref #49581-2
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
2005503Mismatch Repair by IHC Result
* 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
  • Microsatellite Instability
  • MLH1 Promoter Methylation
  • MSI
  • MSI reflex to MLH1 Methylation