NTRK3 and congenital fibrosarcoma: We also strongly recommend the testing for tumors such as secretory carcinoma of the salivary gland (mammary analog secretory carcinoma), secretory breast carcinoma, infantile fibrosarcoma (congenital fibrosarcoma), congenital mesoblastic nephroma, and pediatric high-grade glioma (younger than 3 years old) because ETV6–NTRK3 fusion genes are detected at a high frequency in these diseases (refer to "3.