Sign in →

Test ID TMSI Microsatellite Instability, Tumor

Shipping Instructions


Necessary Information

Pathology report must accompany specimen in order for testing to be performed.

Specimen Required

This assay requires at least 40% tumor nuclei for endometrial specimens and at least 20% tumor nuclei for colorectal specimens

-Preferred amount of tumor area with sufficient percent tumor nuclei: tissue 72 mm(2)

-Minimum amount of tumor area: 18 mm(2)

-These amounts are cumulative over up to 10 unstained slides and must have adequate percent tumor nuclei.

-Tissue fixation: formalin-fixed paraffin-embedded (FFPE), non-decalcified



Specimen Type: Tissue block

Collection Instructions: Submit a formalin-fixed, paraffin-embedded tissue block with acceptable amount of tumor tissue.



Specimen Type: Tissue slide

Slides: 1 stained and 5 unstained

Collection Instructions: Submit 1 slide stained with hematoxylin and eosin and 5 unstained, nonbaked slides with 5-micron thick sections of the tumor tissue.

Note: The total amount of required tumor nuclei can be obtained by scraping up to 5 slides from the same block.

Useful For

Evaluation of tumor tissue to identify patients at high risk for having Lynch syndrome, also known as hereditary nonpolyposis colorectal cancer


Evaluation of tumor tissue for clinical decision-making purposes given the prognostic and therapeutic implications associated with microsatellite instability phenotypes

Testing Algorithm

When this test is ordered, slide review will always be performed at an additional charge.


See Lynch Syndrome Testing Algorithm in Special Instructions.

Method Name

Polymerase Chain Reaction (PCR)

Reporting Name

Tumor, Microsatellite Instability

Specimen Type


Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Ambient (preferred)

Reference Values

An interpretive report will be provided.

Day(s) Performed

Monday through Friday

Report Available

2 to 5 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information


88381-Microdissection, manual

LOINC Code Information

Test ID Test Order Name Order LOINC Value
TMSI Tumor, Microsatellite Instability In Process


Result ID Test Result Name Result LOINC Value
609365 Result Summary 50397-9
609366 Result 43368-0
609367 Interpretation 69047-9
609368 Specimen 31208-2
609369 Source 31208-2
609370 Tissue ID 80398-1
609371 Released By 18771-6

NY State Approved


Additional Tests

Test ID Reporting Name Available Separately Always Performed
SLIRV Slide Review in MG No, (Bill only) Yes