Receptor tyrosine kinases in sinonasal undifferentiated carcinomas--evaluation for EGFR, c-KIT, and HER2/neu expression.

BACKGROUND Our objective was to identify the expression of epidermal growth factor receptor (EGFR), c-KIT (CD117), and HER2/neu in sinonasal undifferentiated carcinoma (SNUC). METHODS Immunohistochemistry for c-KIT (CD117), EGFR, and HER2/neu was performed on paraffin-embedded tissue from SNUC cases. A search for activating mutations in c-kit exons 9, 11, 13, and 17 or gene amplification was undertaken by high-resolution DNA melting curve analysis and fluorescence in situ hybridization (FISH) for c-kit and chromosome 4, respectively. RESULTS By immunohistochemistry, 9 of 11 cases (81.8%) were diffusely (4+) positive for c-KIT, 3 of 11 cases (27.3%) were positive for EGFR, and none of the cases were positive for HER2/neu. Neither activating mutations nor gene amplification of c-kit were detected in any of the 8 assessable tumors. CONCLUSION c-KIT is frequently expressed in SNUC. However, the overexpression is not due to activating mutations or gene amplification.