Diagnostic value of endometrial cytology and related technology

Background Endometrial cytology is not much popular in the world, but is commonly used in a few countries. Although cytomorphological evaluation of endometrial cytology is complicating, recent advance in technology helps improve diagnostic accuracy. In addition, new reporting system, The Yokohama System, has been introduced as a standard reporting system resembling The Bethesda System of the uterine cervical cytology. Although sample standardization is one of the causes in diagnostic problem, it was solved by liquid‐based cytology (LBC) technology. In addition, standardized diagnostic algorithm by cytomorphological assessment of LBC samples, the Osaki Study Group (OSG) method, was recently proposed as a reliable and reproducible method. LBC can be utilized for ancillary methods. Application of immunocytochemistry and molecular technology on endometrial cytology samples has been studied to improve diagnostic accuracy. Recent progress of molecular technology has revealed many driver gene mutations in endometrial cancer and its precursors. Surprisingly, many studies revealed that even normal endometrial tissue had driver gene mutations. Conclusion Based on the recent advance in knowledge of molecular profile of endometrial lesions and normal endometrial tissue, endometrial cytology will gain much power in clinical usefulness.