KIT Gene Immunohistochemistry (IHC)
**Note 1:** Physician statement of KIT IHC can be used to code this data item when no other information is available.
**Note 2:** KIT Gene Immunohistochemistry (IHC) is the expression of the KIT gene in tumor tissue specimens based on immunohistochemical (IHC) stains. A positive test is a diagnostic and predictive marker for GIST tumors. Do not record secondary or acquired mutations that may have developed because of long-term imatinib treatment.
**Note 3:** Other names for KIT are CD117 or c-kit.