Fig. 4

Next-generation sequencing-based and polymerase chain reaction-based microsatellite instability calling methods are highly concordant in both endometrial carcinoma and atypical hyperplasia/endometrial intraepithelial neoplasia specimens. In one discordant case (Case 7), an atypical hyperplasia/endometrial intraepithelial neoplasia specimen exhibited microsatellite instability by next-generation sequencing-based testing and was called microsatellite instability-low by polymerase chain reaction-based testing, and in a second discordant case (Case 8), an atypical hyperplasia/endometrial intraepithelial neoplasia specimen was called microsatellite-stable by next-generation sequencing-based testing and microsatellite instability-low by polymerase chain reaction-based testing. In both cases, this discrepancy reflects the borderline percentage of unstable microsatellites detected by the next-generation sequencing-based method, and both lesions appear to represent a transition between the microsatellite-stable state and an outright microsatellite instability signature. Note that, in Case 11, the top “Carcinoma” cell represents the low-grade carcinoma component, and the bottom “Carcinoma” cell represents the high-grade carcinoma component. AH/EIN, atypical hyperplasia/endometrial intraepithelial neoplasia. MSI, microsatellite instability. MSS, microsatellite-stable. NGS, Next-generation sequencing-based microsatellite instability calling method. PCR, Polymerase chain reaction-based microsatellite instability calling method