MSIHC - Overview: Microsatellite Instability (MSI)/Mismatch Repair (MMR) Protein Immunohistochemistry Profile

Test Catalog

Test Name

Test ID: MSIHC    
Microsatellite Instability (MSI)/Mismatch Repair (MMR) Protein Immunohistochemistry Profile

Useful For Suggests clinical disorders or settings where the test may be helpful

Assessment for defective mismatch repair (dMMR) to identify solid tumors that may respond to anti-PD-L1/PD-1 immunotherapy


Evaluation of colon tumor tissue for evidence of microsatellite instability to stratify prognosis


Identification of individuals at high risk for having hereditary nonpolyposis colorectal cancer (HNPCC)/Lynch syndrome

Genetics Test Information Provides information that may help with selection of the correct genetic test or proper submission of the test request

Both microsatellite instability (MSI) and immunohistochemistry (IHC) testing of tumor tissue are performed to screen individuals for possible hereditary nonpolyposis colorectal cancer/Lynch syndrome, assess for microsatellite instability-high (MSI-H) or defective mismatch repair (dMMR) as a predictor of response to anti-PD-L1/PD-1 immunotherapy (eg, pembrolizumab), to aid in clinical decision making, and to stratify prognosis in colon cancer.

Additional Tests Lists tests that are always performed, at an additional charge, with the initial tests

Test IDReporting NameAvailable SeparatelyAlways Performed
MLH1IMLH-1, ImmunostainNo, (Bill Only)Yes
MSH2IMSH-2, ImmunostainNo, (Bill Only)Yes
MSH6IMSH-6, ImmunostainNo, (Bill Only)Yes
PMS2IPMS-2, ImmunostainNo, (Bill Only)Yes
SLIRVSlide Review in MGNo, (Bill Only)Yes

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

When this test is ordered, slide review, MLH1, MSH2, MSH6, and PMS2 stains will always be performed at an additional charge.


See Hereditary Nonpolyposis Colorectal Cancer Testing Algorithm.

Special Instructions and Forms Library of PDFs including pertinent information and consent forms, specimen collection and preparation information, test algorithms, and other information pertinent to test

Method Name A short description of the method used to perform the test

Microsatellite Instability (MSI): Polymerase Chain Reaction (PCR)/Immunohistochemistry

NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name A shorter or abbreviated version of the Published Name for a test; an abbreviated test name


Aliases Lists additional common names for a test, as an aid in searching

DNA Mismatch Repair-related HNPCC
Hereditary Nonpolyposis Colon Cancer (HNPCC)
Immunohistochemistry (IHC)
Lynch Syndrome
Microsatellite Instability (MSI)
Tumor Microsatellite Instability (MSI)
Hereditary Non-Polyposis