Colorectal Cancer – Microsatellite Instability by PCR

Detects instability of microsatellite loci associated with a loss or suppression of DNA mismatch repair system. Detects instability in 5 mononucleotide markers.

CPT Codes:

83890(2), 83900(2), 83901(6), 83907, 83909(2), 83912-26

Specimen Requirements:

Please Note: This assay requires submission of a sample of normal colonic tissue (peripheral blood, known non-tumorous colonic mucosa) for colorectal comparison.

1. Peripheral Blood (for control for MSI):

• 10-20 ml in EDTA (lavender-top) tube.
• Refrigerate specimen. Use cold pack for transport. Be sure cold pack is not in direct contact with specimen during transport.

2. Fixed Paraffin Block with Corresponding H&E:

• Tissue should be well-fixed in formalin. If alternative fixative is used, it should be noted on the requisition. Average tissue size 5 mm.
• 0.2 cm x 0.2 cm x 0.2 cm tissue.
• Store specimen at room temperature (>16°C).
• Use cold pack for transport. Be sure cold pack is not in direct contact with specimen during transport.

3. Precut 5-10 Slides of Microsections from Each Paraffin Block Submitted

Turnaround Time:

6-7 days

Related Terms: colonic cancer