MSI is typically detected through molecular testing. The most common methods include PCR-based assays and next-generation sequencing (NGS). These tests compare the length of microsatellite sequences in tumor DNA to those in normal tissue DNA. Significant differences indicate MSI. Another approach involves immunohistochemistry (IHC) to detect the presence or absence of MMR proteins like MLH1, MSH2, MSH6, and PMS2.
