Practical usefulness of atypical endometrial cell categories within the new classification of endometrial cytology when applied to conventional smears

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.

Application of immunocytochemical and molecular analysis of six genes in liquid-based endometrial cytology

BACKGROUND

The Yokohama System of Endometrial Cytology has been used for reporting endometrial cytology, which includes gray zone category, atypical endometrial cells (ATEC), subdivided into ATEC-US and ATEC-AE. ATEC-US has been reported to be correlated with malignancy in nearly 10% of the cases. For accurate diagnosis, application of ancillary techniques on endometrial cytology was investigated.

METHODS

Thirty-seven liquid based cytological specimens (SurePath™) with diagnosis of ATEC or malignant which have corresponding histological specimens, were subjected to immunocytochemical analysis for β-catenin, ARID1A, and PTEN. Hot spots of mutations for KRAS, BRAF and PIK3CA were evaluated by using i-densy system (ARKRAY).

RESULTS

In endometrial samples with the diagnosis of ATEC and malignant, aberrant gene expressions and/or gene mutations for β-catenin, ARID1A, PTEN, KRAS, BRAF, and PIK3CA were observed in 32.4, 18.9, 37.8, 18.8, 0, and 37.1%, respectively. When any of the genes had aberrant expression or mutation, only sensitivity was better than that of cytology (77 vs. 53.8%). However, specificity, positive predictive value, negative predictive value, and accuracy was better in cytology than those of ancillary techniques. Increasing rate of abnormality according to the consequent histology results was observed in ARID1A (p = .015). Frequent loss of PTEN immunostaining (45.8%) and PIK3CA mutation (43.5%) was observed in the cases with consequent benign histology results.

CONCLUSION

In ATEC category of endometrial cytology, gene expression and mutation analysis of six genes were insufficient to aid conventional cytological diagnoses albeit increased sensitivity. Further investigation would be necessary.

Evaluation of the benefit and use of the new terminology in endometrial cytology reporting system

OBJECTIVE

The introduction and establishment of a new classification system for endometrial cytology, the "New Terminology in Endometrial Cytology (NTEMC) system," which is based on the Bethesda System for uterine cervical cytology, has recently been reported. However, the clinical management for new categories in the NTEMC system, particularly atypical endometrial cells (ATEC), has not been clarified. The objective of the present study is to determine how the ATEC category should be treated and whether the introduction of the system has decreased the number of unnecessary endometrial biopsies.

METHODS

Fifty-nine cases were diagnosed as "suspicious positive" according to the three-tier reporting (TTR) system, which was adopted in Japan. The specimens were re-evaluated according to the NTEMC system. Thirty-seven of the 59 patients underwent endometrial biopsy. We correlated the pathological diagnosis with the NTEMC system category.

RESULTS

The 59 cases were classified according to the NTEMC system as follows: 36 cases were classified as ATEC of undetermined significance (ATEC-US), 21 cases were classified as ATEC for which atypical endometrial hyperplasia or worse cannot be excluded (ATEC-A), and 2 cases were classified as endometrial hyperplasia. The ratio of atypical endometrial hyperplasia or malignancy in ATEC-US category was significantly lower than that in ATEC-A category. Fifteen cases in ATEC-US category did not show atypical endometrial hyperplasia lesions or malignancy after 3 months.

CONCLUSIONS

These data suggest that patients with ATEC-US results can be followed up for at least three months, and the introduction of the NTEMC system decreased the number of unnecessary endometrial biopsies.