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Published on: June 7, 2019
KIT gene mutations and patterns of protein expression in mucosal and acral melanoma
Suzan Abu-Abed1, Nancy Pennell, Teresa Petrella
1Department of Anatomical Pathology, Sunnybrook Health Sciences Centre, Toronto, ON.
Background:
Recently characterized KIT (CD117) gene mutations have revealed new pathways involved in melanoma pathogenesis. In particular, certain subtypes harbor mutations similar to those observed in gastrointestinal stromal tumors, which are sensitive to treatment with tyrosine kinase inhibitors.
Objective:
The purpose of this study was to characterize KIT gene mutations and patterns of protein expression in mucosal and acral melanoma.
Methods:
Formalin-fixed, paraffin-embedded tissues were retrieved from our archives. Histologic assessment included routine hematoxylin-eosin stains and immunohistochemical staining for KIT. Genomic DNA was used for polymerase chain reaction-based amplification of exons 11 and 13.
Results:
We identified 59 acral and mucosal melanoma cases, of which 78% showed variable levels of KIT expression. Sequencing of exons 11 and 13 was completed on all cases, and 4 (6.8%) mutant cases were isolated.
Conclusion:
We successfully optimized conditions for the detection of KIT mutations and showed that 8.6% of mucosal and 4.2% of acral melanoma cases at our institution harbor KIT mutations; all mutant cases showed strong, diffuse KIT protein expression. Our case series represents the first Canadian study to characterize KIT gene mutations and patterns of protein expression in acral and mucosal melanoma.
Insights
KIT gene mutations are implicated in melanoma pathogenesis. This study found KIT mutations in 8.6% of mucosal and 4.2% of acral melanoma cases, with strong KIT protein expression in all mutant cases.
Area of Science:
- Oncology
- Genetics
- Dermatology
Background:
- KIT (CD117) gene mutations are increasingly recognized in melanoma development.
- Mutations in KIT are similar to those in gastrointestinal stromal tumors, which respond to tyrosine kinase inhibitors.
Purpose of the Study:
- To investigate KIT gene mutations and protein expression in mucosal and acral melanoma.
- To characterize the prevalence and patterns of KIT alterations in these melanoma subtypes.
Main Methods:
- Analysis of formalin-fixed, paraffin-embedded melanoma tissues.
- Histologic assessment using hematoxylin-eosin and KIT immunohistochemical staining.
- Polymerase chain reaction amplification and sequencing of KIT exons 11 and 13.
Main Results:
- KIT expression was observed in 78% of the 59 acral and mucosal melanoma cases analyzed.
- KIT mutations in exons 11 and 13 were identified in 4 cases (6.8%).
Conclusions:
- Optimized methods for detecting KIT mutations in melanoma were established.
- KIT mutations were found in 8.6% of mucosal and 4.2% of acral melanoma cases.
- All identified KIT mutations were associated with strong, diffuse KIT protein expression.
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