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Updated: Aug 29, 2026
Robotic Duodenal Sleeve Resection for Gastrointestinal Stromal Tumor with Rare Exon 8 KIT Mutation Following Neoadjuvant Imatinib
Published on: April 3, 2026
Rare KIT (CD117) expression in multiple myeloma abrogates the usefulness of imatinib mesylate treatment
1Institute of Pathology, Kantonsspital Basel, Schönbeinstrasse 40, 4031, Basel, Switzerland.
Background:
Imatinib mesylate blocks the tyrosine kinase activity of KIT (CD117) and is an effective treatment for gastrointestinal stromal tumors. In multiple myeloma, KIT expression has been detected by flow cytometry in about 33% of specimens, but no previous immunohistochemical assessment has yet been made of the expression pattern of KIT.
Materials And Methods:
We performed immunohistochemical analyses of 100 patients, including 72 with multiple myeloma (MM), 8 with lymphoplasmacytic lymphoma (LPL), 10 with monoclonal gammopathy of undetermined significance (MGUS) and 10 with reactive plasmocytosis. One KIT-positive MM was sequenced using polymerase chain reaction analysis.
Results:
In MM, only 2 cases (2.8%) were KIT positive. The great majority of the cases (97, 2%) did not express the KIT receptor tyrosine kinase. No mutation of the c-kit gene was detected.
Conclusions:
KIT expression is a rare event in MM and not detectable in MGUS and LPL. Therefore, treatment with imatinib is unlikely to be effective in these patients.
Insights
KIT expression is rare in multiple myeloma (MM), with only 2.8% of cases positive. This suggests imatinib treatment is unlikely to benefit most MM, MGUS, or LPL patients.
Area of Science:
- Oncology
- Hematology
- Molecular Biology
Background:
- Imatinib mesylate targets KIT (CD117) tyrosine kinase, effective for gastrointestinal stromal tumors.
- KIT expression in multiple myeloma (MM) was previously assessed by flow cytometry (approx. 33% positivity).
- No prior immunohistochemical studies evaluated KIT expression patterns in MM.
Purpose of the Study:
- To determine the immunohistochemical expression of KIT in multiple myeloma (MM).
- To assess KIT expression in related plasma cell disorders.
- To evaluate the potential efficacy of imatinib in these conditions.
Main Methods:
- Immunohistochemical analysis of KIT expression in 100 patients.
- Included 72 MM, 8 lymphoplasmacytic lymphoma (LPL), 10 monoclonal gammopathy of undetermined significance (MGUS), and 10 reactive plasmocytosis cases.
- Polymerase chain reaction sequencing of the c-kit gene in one KIT-positive MM case.
Main Results:
- KIT expression was detected in only 2.8% (2/72) of multiple myeloma cases.
- The vast majority (97.2%) of MM cases did not express the KIT receptor tyrosine kinase.
- No mutations in the c-kit gene were identified, and KIT was not detected in MGUS or LPL.
Conclusions:
- KIT receptor tyrosine kinase expression is a rare event in multiple myeloma.
- KIT is not detectable in monoclonal gammopathy of undetermined significance or lymphoplasmacytic lymphoma.
- Imatinib treatment is unlikely to be effective for most patients with these conditions due to low KIT expression.
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