Microsatellite Instability

Test ID: 

706641

CPT code:

81301

Synonyms:

• Colorectal Cancer Screening
• Hereditary Nonpolyposis Colorectal Cancer, Screening
• Mismatch Repair Defect
• Replication Repair (RER)

Clinical Use:

Identify tumors with microsatellite instability. High-frequency microsatellite instability (MSI-H) is associated with Lynch syndrome, but it is also found in 15% to 20% of sporadic colorectal and endometrial cancers. Lynch syndrome is an autosomal-dominant inherited cancer syndrome that predisposes to colorectal, endometrial, gastric, ovarian, upper urinary tract, and other cancers.

Specimen Type:

One paraffin-embedded tumor and either whole blood or paraffin-embedded normal tissue

Requested Volume: 

Eight unstained slides at 5 μM and one matching H&E slide or FFPE tissue block or 3-5 mL whole blood. Samples with ≥4 mm² tumor and normal tissue surface area and ≥50% tumor content are preferred.

Container Type: 

FFPE tissue block or slides, lavender-top (EDTA) tube, or green-top (sodium heparin) tube

Storage Instructions:

Blocks and slides at room temperature; whole blood at 2°C to 8°C

Rejection Criteria

Tumor block containing insufficient tumor tissue or no tumor; broken or stained slides. Whole blood: Contaminated specimen; frozen whole blood received; leaking tube; clotted blood; hemolysis; specimen containing suspicious foreign material; quantity not sufficient for analysis