Fig. 6

Comparison of somatic mutations and percentage of unstable microsatellite loci in paired atypical hyperplasia/endometrial intraepithelial neoplasia and carcinoma specimens. Thirteen of 17 paired atypical hyperplasia/endometrial intraepithelial neoplasia and carcinoma specimens shared at least one pathogenic somatic mutation in a gene known to be significant in pathogenesis of endometrioid endometrial carcinoma [36,37,38]. A single case (Case 2) showed shared biallelic pathogenic mutations in a mismatch repair protein gene (MSH2), which was not present on germline testing. In two cases (Cases 4 and 13) lacking a shared somatic mutation in an endometrial carcinoma-related gene, substantial overlap of unstable microsatellite loci was observed between atypical hyperplasia/endometrial intraepithelial neoplasia and carcinoma specimens, favoring a clonal relationship. AH, atypical hyperplasia/endometrial intraepithelial neoplasia. EC, endometrial carcinoma. NGS-MSI (%), percentage of unstable microsatellite loci on next-generation sequencing-based microsatellite instability testing. PCR-MSI, polymerase chain reaction-based microsatellite testing result (MSS, microsatellite stable; MSI-L, microsatellite instability-low; MSI-H, microsatellite instability-high)