Collaborative Stage

Note 1: This is a special molecular diagnostic test performed on tumor tissue to identify mutations in specific parts (called exons) of the KIT gene. Certain patterns of mutations correlate with the anatomic site and morphology of gastrointestinal stromal tumors (GISTs) tumors and can predict response to treatment with agents such as imatinib mesylate (Gleevec) and sunitinib malate (Sutent). Some mutations are associated with acquired resistance to imatinib treatment; do not record secondary or acquired mutations that may have been caused by long-term imatinib treatment.
Note 2: Code the mutation locations found from the KIT gene test. Another name for KIT is CD117.
Note 3: See CS Site-Specific Factor 7 for coding information about KIT expression detected with immunohistochemistry (IHC). See CS Site-Specific Factor 9 for coding information about mutations of the PDGFRA gene.

Code	Description
000	KIT gene test negative for mutations; no mutations; normal or wild-type gene
010	KIT gene test positive for mutation of exon 9 only
020	KIT gene test positive for mutation of exon 11 only
030	KIT gene test positive for mutation of exon 13 only
040	KIT gene test positive for mutation of exon 17 only
800	KIT gene test positive for one other specified mutation
810	KIT gene test positive for more than one specific mutation
850	KIT gene test positive, NOS; mutation(s) found but the specific mutation(s) are not stated
988	Not applicable: Information not collected for this case (If this information is required by your standard setter, use of code 988 may result in an edit error.)
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

CS Site-Specific Factor 8
KIT Gene Mutations