IHC - Microsatellite Instability Panel for Colorectal Carcinoma (MLH-1, MSH-2, MSH- 6, PMS-2)

The IHC – Microsatellite Instability (MSI) Panel for Colorectal Carcinoma (MLH1, MSH2, MSH6, PMS2) is a comprehensive immunohistochemistry (IHC) diagnostic test used to evaluate DNA mismatch repair (MMR) protein expression in colorectal cancer tissue samples. This panel detects the presence or absence of four critical mismatch repair proteins: MLH1, MSH2, MSH6, and PMS2.

These proteins are responsible for correcting DNA replication errors. When one or more of these proteins are missing, the DNA repair system becomes defective, causing microsatellite instability (MSI). MSI is strongly associated with certain colorectal cancers and may indicate Lynch syndrome, a hereditary condition that increases the risk of colorectal and other cancers.

This panel is considered a standard molecular screening tool in colorectal cancer evaluation because it helps determine hereditary cancer risk and identifies patients who may benefit from immunotherapy and precision-targeted treatment.

Benefits of the Test

The MSI panel offers several important clinical benefits:

• Detects loss of MLH1, MSH2, MSH6, and PMS2 proteins
• Identifies mismatch repair deficiency (dMMR)
• Screens for Lynch syndrome
• Supports accurate colorectal cancer classification
• Helps guide immunotherapy treatment decisions
• Assesses hereditary cancer risk for family screening
• Improves personalized cancer management

This panel provides a complete molecular pathology assessment for colorectal carcinoma.

Why Doctors Recommend This Test

Doctors recommend the MSI panel for patients diagnosed with colorectal carcinoma or when hereditary mismatch repair deficiency is suspected.

It is commonly advised for:

• Newly diagnosed colorectal cancer patients
• Early-onset colorectal carcinoma cases
• Patients with family history of colorectal or Lynch syndrome-related cancers
• Cases requiring advanced molecular tumor profiling
• Patients being evaluated for immunotherapy eligibility

The results help oncologists identify treatment options and determine if genetic counseling is needed.

Preparation Before Test

No special preparation is required from the patient. The panel is performed on previously collected colorectal tissue biopsy or surgical tumor specimens.

Normal Reporting Time

The typical turnaround time for the MSI panel is 3 to 5 working days, depending on laboratory processing and tissue complexity.

Who Should Take This Test

This test is recommended for:

• Patients diagnosed with colorectal carcinoma
• Individuals with family history of hereditary colorectal cancers
• Patients suspected of Lynch syndrome
• Cases requiring mismatch repair deficiency screening
• Oncology patients needing precision treatment planning

The IHC MSI Panel for Colorectal Carcinoma is a critical diagnostic tool in modern oncology. It helps identify mismatch repair defects, evaluate inherited cancer risk, and guide personalized treatment strategies. Early detection improves patient outcomes and supports preventive screening for family members.