BRAF mutations in pediatric metanephric tumors.

Area of Science:

• Pediatric Oncology
• Nephropathology
• Cancer Genetics

Background:

• Metanephric neoplasms are rare kidney tumors, with metanephric adenoma and adenofibroma being uncommon, especially in children.
• Genetic analysis of metanephric tumors has not consistently shown chromosome alterations typical of adult renal cell carcinoma, suggesting a distinct origin for associated carcinomas.

Purpose of the Study:

• To investigate the genetic relationship between metanephric adenoma and associated papillary carcinoma in pediatric cases.
• To evaluate the diagnostic utility of the BRAF V600E mutation in pediatric metanephric tumors.

Main Methods:

• Analysis of 4 pediatric metanephric tumors, including one with a composite adenofibroma and papillary carcinoma.
• Utilized single nucleotide polymorphism array and fluorescence in situ hybridization to assess copy number alterations.
• Performed BRAF V600E immunostaining and sequencing on tumor components and compared with pediatric renal cell carcinoma and Wilms tumor.

Main Results:

• No copy number alterations were detected in either the adenoma or carcinoma components of the composite tumor.
• Three of the four pediatric cases, including the composite tumor, harbored a BRAF V600E mutation in both adenoma and carcinoma components.
• BRAF V600E immunostaining was negative in pediatric renal cell carcinoma and Wilms tumor, distinguishing them from metanephric adenoma.

Conclusions:

• The shared BRAF V600E mutation provides the first genetic evidence linking metanephric adenoma and associated carcinoma in pediatric patients.
• BRAF V600E immunostaining serves as a valuable diagnostic marker for pediatric metanephric adenoma.
• Further research is needed to elucidate the role of BRAF V600E in the pathogenesis of renal carcinoma arising in this context.