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HelpTest Code LAB8603 Mismatch Repair (MMR) Protein Immunohistochemistry Only, Tumor
Additional Codes
IHC
Useful For
Evaluating tumor tissue to identify patients at risk for having hereditary nonpolyposis colon cancer/Lynch syndrome
Additional Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| MLH1I | MLH-1, Immunostain | No, (Bill only) | Yes |
| MSH2I | MSH-2, Immunostain | No, (Bill only) | Yes |
| MSH6I | MSH-6, Immunostain | No, (Bill only) | Yes |
| PMS2I | PMS-2, Immunostain | No, (Bill only) | Yes |
Testing Algorithm
When this test is ordered, MLH1, MSH2, MSH6, and PMS2 stains will always be performed at an additional charge.
For more information see Lynch Syndrome Testing Algorithm.
Special Instructions
Method Name
Immunohistochemistry (IHC)
Specimen Type
VariesNecessary Information
Pathology report (final or preliminary), at minimum containing the following information, must accompany specimen for testing to be performed:
1. Patient name
2. Block number-must be on all blocks, slides, and paperwork (can be handwritten on the paperwork)
3. Tissue collection date
4. Source of the tissue
Specimen Required
Tumor tissue is required.
Preferred: Submit both of the following specimens.
Acceptable: Submit at least one of the following specimens.
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 Hematoxylin and eosin-stained and 10 unstained
Collection Instructions:
Submit the followings slides:
1 Slide stained with hematoxylin and eosin
AND
10 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 10 slides from the same block.
Additional Information: Unused unstained slides will not be returned.
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Varies | Ambient (preferred) | |
| Refrigerated | ||
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Reference Values
An interpretive report will be provided.
Interpretation
The interpretation of molecular biomarker analysis includes an overview of the results and the associated diagnostic, prognostic, and therapeutic implications.
Method Description
Immunohistochemistry staining is used to determine the presence or absence of protein expression for MLH1, MSH2, MSH6, and PMS2. Lymphocytes and normal epithelium exhibit strong nuclear staining and serve as positive internal controls for staining of these proteins.(Cunningham JM, Kim CY, Christensen ER, et al. The frequency of hereditary defective mismatch repair in a prospective series of unselected colorectal carcinomas. Am J Hum Genet. 2001;69[4]:780-790; Gill S, Lindor NM, Burgart LJ, et al. Isolated loss of PMS2 expression in colorectal cancers: frequency, patient age, and familial aggregation. Clin Cancer Res. 2005;11[18]:6466-6471)
Day(s) Performed
Varies
Report Available
5 to 8 daysSpecimen Retention Time
Tissue blocks: Unused portions of blocks will be returned; Tissue slides: Unused slides are stored for at least 5 yearsPerforming Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
88341 MLH1, MLH2, or MLH6 (if appropriate)
88342 PMS2 (if appropriate)
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| IHC | MMR Protein, IHC Only, Tumor | In Process |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 53258 | Result Summary | 50397-9 |
| 53259 | Result | In Process |
| 54443 | Interpretation | 59465-5 |
| 53260 | Specimen | 31208-2 |
| 53261 | Source | 31208-2 |
| 54444 | Tissue ID | 80398-1 |
| 53262 | MLH1 IHC | 81691-8 |
| 53263 | MSH2 IHC | 81692-6 |
| 53264 | MSH6 IHC | 81693-4 |
| 53265 | PMS2 IHC | 81694-2 |
| 53266 | Released By | 18771-6 |
Forms
1. Molecular Genetics: Inherited Cancer Syndromes Patient Information (T519)
2. If not ordering electronically, complete, print, and send an Oncology Test Request (T729) with the specimen.