Site-Specific Factor 12

KIT Gene Immunohistochemistry (IHC)


**Note 1:** Most gastrointestinal stromal tumors (GISTs) have oncogenic mutations of the KIT gene, which is located on chromosome 4q. KIT is a cytokine receptor which binds to stem cell factor, which causes certain types of cells to grow; altered forms of KIT may be associated with some types of cancer. This test detects expression of the KIT gene in tumor tissue sections using immunohistochemical (IHC) stains. Test results are available in the pathology report. A positive test helps to establish the diagnosis of GIST and to identify patients for whom treatment with agents such as imatinib mesylate (Gleevec) or sunitinib malate (Sutent) is appropriate. Do not record secondary or acquired mutations that may have developed because of long-term imatinib treatment. **Note 2:** Another name for KIT is CD117. **Note 3:** See **Site-Specific Factor 13, KIT Gene Mutations** for coding information about specific mutations of the KIT gene detectable with molecular testing.  **Note 4:** See **Site-Specific Factor 14, PDGFRA Gene Mutation** for coding information about mutations of the PDGFRA gene. .




NAACCR #2866


Code Description
010 Positive/elevated
020 Negative/normal; within normal limits
030 Borderline; undetermined whether positive or negative
988 Not applicable: Information not collected for this case
997 Test ordered, results not in chart; results pending
998 Test not done (test not ordered and not performed)
999 Unknown or no information
Not documented in patient record