Microsatellite Instability PCR with Interpretation
Label Mnemonic: MSI
Epic code: LAB1980
Order form: Molecular Oncology Requisition
Supply order: Supply Order Form
Billing: Billing Policies
CPT code: 81301
Formalin fixed, paraffin embedded tissue block or 10 unstained 5-10 μM slides at 20-25°C and an H&E slide of the tissue
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:
Turn Around Time:
7-10 working days
Reference Range:
Microsatellite Stable
Multiplex PCR followed by Fluorescence Capillary Electrophoresis
Submit formalin fixed, paraffin embedded tissue block or 10 unstained
5-10 μM slides and an H&E slide along with the requisition. Please include surgical pathology report and relevant clinical information.

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.
Sample Processing:
Formalin-fixed, paraffin embedded tissue should be submitted.
Submit a whole blood EDTA specimen from the same patient or tissue from an unaffected area (formalin-fixed, paraffin embedded tissue) of the same patient.
Label transport tube with two patient identifiers, date and time of collection.
Lavender tube is sent as whole blood, no processing necessary.
Relevant clinical information must be submitted with specimen in order to provide correct interpretation of test results.
Specimen source is required on requisition for processing.
Sample Storage:
Tissue Specimen - Freeze immediately and store frozen or send Formalin-fixed paraffin embedded blocks.
Transport Instructions:
Place requisition into outside pocket of bag.
Place specimen into zip-lock type bag, seal bag.
Place coolant packs into Styrofoam container.
Coolant packs up to 8 hours.
Frozen Tissue - Ship frozen on dry ice. Ship express mail with overnight delivery. Formalin-fixed paraffin embedded blocks ship at room temperature.
Protect block or slides from excessive heat and ship in cooled container during summer months.
CPT Code: