Microsatellite Instability PCR with Interpretation
Label Mnemonic: MSI
Epic Lab Code: LAB1980
Downtime Form: A-1a Molecular Pathology/Diagnostics Laboratory Requisition
Molecular Pathology
6004 BT GH
384-9568
Specimen(s):
Formalin fixed, paraffin embedded tissue block and 10 unstained 5-10 μM slides at 20-25°C and an H&E slide of the tissue
Minimum:
Tumor cells more than 50% of the total tissue and greater than 10mm2 in surface area on the block.

Must also submit a healthy tissue specimen or peripheral blood from the same subject for comparison of microsatellite markers.
Rejection Criteria:
Specimens fixed in B5 fixative or that have been decalcified will not be accepted. Tumor specimens containing less than 50% tumor cells or are less than 10mm2 in area may be unacceptable.
Testing Schedule:
Weekly
Turn Around Time:
7-10 working days
Reference Range:
Microsatellite Stable
Comments:
Tumor tissue and normal tissue should be obtained as part of the surgical procedure for testing. The tissue should be formalin-fixed, paraffin embedded and reviewed by a surgical pathologist prior to MSI testing. A block containing normal tissue (non-tumor) should be submitted for testing in addition to a block containing at least 50% tumor. Acceptable tissue for the non-tumor block is tissue with a high nuclear content, preferably benign lymph node tissue if available. Blood submitted in EDTA or sodium citrate is acceptable for the normal block if tissue is not available. An H&E stained glass slide from both blocks should also be submitted.
Methodology:
Multiplex PCR followed by Fluorescence Capillary Electrophoresis
CPT Code:
81301