Professional
Technical
IVT
MSI-H
Pronunciation: M-S-I-high
Also written as: MSI-H — Microsatellite Instability-High
Microsatellite instability-high status indicating defective DNA mismatch repair in tumors.
Full Definition
Microsatellite instability-high represents a tumor phenotype characterized by widespread alterations in microsatellite sequences due to deficient DNA mismatch repair mechanisms. This condition occurs in approximately 15% of colorectal cancers and smaller percentages of other tumor types. MSI-H tumors typically respond well to immune checkpoint inhibitor therapy due to high neoantigen burden and immune infiltration.
Usage
Usage note: Always hyphenate. Distinguish from MSI-L (microsatellite instability-low).
In Context
- "The MSI-H status qualified the patient for pembrolizumab therapy regardless of tumor site." — Treatment recommendation
- "Immunohistochemistry confirmed the MSI-H result obtained through PCR analysis." — Pathology correlation report
Also known as
microsatellite instability-high
MMR-deficient
Contrasted with
MSS
MSI-L
MMR-proficient
Don't confuse with
MSI-L
MMR status