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.
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.

Compliance Category

Laboratory Developed Test (LDT)


If MLH1 is abnormal for Mismatch Repair by IHC, then MLH1 Promoter Methylation will be added. Additional charges apply.

Hotline History
CPT Codes

88342; 88341 x3; if reflexed, add 81288; 88381

Component Test Code* Component Chart Name LOINC
0049199 Client Case or Ref # 49581-2
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
2005503 Mismatch Repair by IHC Result
3002969 MSI Tissue Source
* 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 click the sidebar link to access the Interface Map.
  • Microsatellite Instability
  • MLH1 Promoter Methylation
  • MSI
  • MSI reflex to MLH1 Methylation
Mismatch Repair by Immunohistochemistry with Reflex to MLH1 Promoter Methylation