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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:
Specimen Type: Tissue block
Collection Instructions: Submit formalin-fixed, paraffin-embedded tissue block.
Acceptable:
Specimen Type: Tissue slide
Slides: 1 Hematoxylin and eosin stained and 10 unstained
Collection Instructions: Submit 1 slide stained with hematoxylin and eosin and 10 unstained, nonbaked slides (5-micron-thick sections) of tumor tissue.
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Varies | Ambient (preferred) | ||
| Refrigerated | |||
Reject Due To
| Specimens that have been decalcified (all methods) Specimens that have not been formalin-fixed, paraffin-embedded Bone marrow in EDTA |
Reject |
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
FFPE tissue: Unused portions of FPPE blocks will be returned. Unused, unstained slides: 5 years; Stained slides: Indefinitely.Performing 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.