Utility of thin-layer preparations in the endometrial cytology

A review of the directly sampled endometrial cytology on LBC samples: Classification, microscopic criteria and beyond

The Yokohama System for Reporting Endometrial Cytology (TYS) has been proposed by an expert meeting under the auspices of the International Academy of Cytology (IAC) in May 2016 at the IAC in Yokohama. Since its introduction, the TYS has been receiving worldwide acceptance, and this review aims to assess its global impact. The adoption of endometrial cytology as a diagnostic procedure has been hampered in the past by difficulties arising in interpreting the cellular findings due to a number of factors (such as excess blood, cellular overlapping and the complex physiology of endometrium). Recently, the use of liquid-based cytology (LBC), with its ability to remove blood and mucus and to distribute cells uniformly in a thin layer on the slide, has provided an opportunity to re-evaluate the role of endometrial cytology. LBC is a useful tool in the cytologic diagnosis and follow-up of endometrial abnormalities, which remains complementary to the emerging molecular diagnostic cytopathology. The study of LBC from endometrial cytology could be challenging since it is affected by numerous look-alikes and diagnostic pitfalls. This review discusses these various entities and takes into consideration the ancillary techniques that may be useful in the diagnostic procedure. In conclusion, our review of the published data suggests that the TYS is a valid classification scheme that has been widely accepted by cytopathologists globally, is highly reproducible and makes a valuable contribution to clinical therapeutic management. At present, molecular cytopathology is a rapidly evolving field of modern cytopathology, which underlines the effective interplay between genomics and cytology. This review aims to provide a comprehensive review of the drawbacks of endometrial cytopathology, particularly in terms of endometrial cancer diagnosis and molecular testing.

Morphological Differences between Liquid-Based Cytology and Conventional Preparation in Endometrial Endometrioid Carcinoma Grade 1 and Grade 3, and the Differentiation of Grades in Each Method

INTRODUCTION

Direct smearing preparation (conventional preparation [CP]) has been widely used for endometrial cytology in Japan. In CP, sampling and screening errors are problematic. In liquid-based cytology preparation (LBC), the problems of CP can be solved. But there is a problem that cytological findings of LBC are different from those of CP. The purpose of this study was to evaluate the differences of morphological findings of endometrial cytology between LBC and CP, and the usefulness of the endometrial LBC to differentiate endometrioid carcinoma grade 1 (G1) from grade 3 (G3).

METHODS

Thirteen cases of endometrioid carcinoma G1, and 5 cases of G3 collected by the Softcyte device and prepared by LBC and CP (split specimen) were used. We focused on the following items: (1) the number of clusters per cm2, (2) the number of layers of clusters, (3) area of clusters, (4) perimeter of clusters, (5) roundness of clusters, (6) complexity of clusters, (7) area of nucleus, (8) perimeter of nucleus, (9) roundness of nucleus, (10) complexity of nucleus, (11) area of nucleolus, and (12) nucleolus-nucleus ratio (N/N).

RESULTS

Compared with CP, the number of clusters and layers of the clusters in LBC were significantly larger in G1. The area and perimeters of the clusters and the nucleus were significant smaller, and the N/N ratio was greater in LBC than that in CP in both G1 and G3. Regarding morphological differences between G1 and G3 in LBC and CP, the number of layers was significantly larger in G1 than in G3 in LBC and CP. The area of the clusters in LBC was significantly larger in G1 than in G3. The area and perimeters of the nucleus in CP and the area of the nucleolus and N/N ratio in LBC and CP were significantly smaller in G1 than in G3.

CONCLUSION

In the endometrial cytology, it became clear that the cell image was different between LBC and CP and between G1 and G3. By microscopic examination understanding the characteristics of the cell image in LBC, endometrial LBC could be useful to diagnose endometrial carcinoma.

A Diagnostic Approach to Endometrial Cytology by Means of Liquid-Based Preparations

The adoption of endometrial cytology as a diagnostic procedure has been hampered in the past by difficulties arising in interpreting the cellular findings due to a number of factors (such as excess blood, cellular overlapping, and the complex physiology of endometrium). Recently, the use of liquid-based cytology (LBC), with its ability to remove blood and mucus and to distribute cells uniformly in a thin layer on the slide, has provided an opportunity to reevaluate the role of endometrial cytology. LBC samples are easier to screen compared to conventional ones, due to a smaller screening area and an excellent quality of cell preparations. LBC by using peculiar cytoarchitectural features is a useful tool in the cellular diagnosis and follow-up of abnormalities, which, however, remains complementary to histopathology and to the emerging molecular diagnostic cytopathology. This review discusses these various entities and takes into consideration the ancillary techniques that may be useful in the diagnostic procedure. Herein, we also summarize the process and rationale by which updates were made to the standardized terminology in 2018 and outline the contents of the new Bethesda-style classification (the Yokohama system) for the endometrial cytology.

Evaluation of cellular adequacy in endometrial liquid-based cytology

OBJECTIVE

This study evaluated cellular adequacy in endometrial liquid-based cytology (LBC) specimens.

METHODS

In total, 1267 cases were obtained and the rate of unsatisfactory specimen and diagnostic accuracy for malignancy were assessed. If ≥10 cellular clusters composed of ≤30 endometrial cells were found per specimen, then the sample was provisionally considered adequate.

RESULTS

The unsatisfactory rate (with fewer than 10 clusters) was 15.4%. Diagnostic accuracy in specimens with ≥10 clusters was significantly higher (90.5% vs 36.4%) than that in specimens with fewer than10 clusters. Moreover, the unsatisfactory rate in patients aged ≥60 years was significantly higher (33.8% vs 13.2%) than that in patients younger than 60 years. Although the unsatisfactory rate was decreased, significant differences were not found between cases with fewer than five clusters (22.6%) and fewer than 10 clusters (33.8%) in patients aged ≥60 years. Diagnostic accuracy in cases with five or more clusters was significantly higher (90.3% vs 0%) than that in cases with fewer than five clusters.

CONCLUSIONS

We propose that ≥10 clusters with ≥30 endometrial cells per cluster could be used as a specimen adequacy criterion for endometrial LBC. If ≥10 clusters cannot be found in patients aged ≥60 years, then the use of the alternative criterion of five or more clusters may yield satisfactory specimen adequacy.

Endometrial Cytology as a Method to Improve the Accuracy of Diagnosis of Endometrial Cancer: Case Report and Meta-Analysis

More and more researchers have reported that dilatation and curettage (D&C) or Pipelle had low accuracy, high misdiagnosis, and insufficient rate. Endometrial cytology is often compared with histology and seems to be an efficient method for the diagnosis of endometrial disorders, especially endometrial cancer. We report a case of misdiagnosed endometrial cancer by D&C, but with a positive cytopathological finding. Following that, a meta-analysis including 4,179 patients of endometrial diseases with cyto-histopathological results was performed to assess the value of the endometrial cytological method in endometrial cancer diagnosis. The pooled sensitivity and specificity of the cytological method in detecting endometrial atypical hyperplasia or cancer was 0.91[95% confidence interval (CI) 0.74-0.97] and 0.96 (95% CI 0.90-0.99), respectively. The pooled positive likelihood ratio and negative likelihood ratio was 25.4 (95% CI 8.1-80.1) and 0.10 (95% CI 0.00-0.30), respectively. The diagnostic odds ratio which was usually used to evaluate the diagnostic test performance reached 260 (95% CI 36-1905). So we recommend that D&C and Pipelle are still practical procedures to evaluate the endometrium, cytological examinations should be utilized as an additional endometrial assessment method.

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.

Liquid-based endometrial cytology associated with curettage in the investigation of endometrial carcinoma in a population of 1987 women

PURPOSE

The aim of this study was to investigate the diagnostic accuracy of liquid-based endometrial cytology, in comparison with histology.

METHODS

1987 patients scheduled for hysteroscopy were enrolled in this study. All patients proceeded sequentially through endometrial cytology, hysteroscopy and then dilatation and curettage (D&C). Cytology sampling was performed by brushing the uterus cavity using SAP-1 and the sample was prepared to liquid-based smear using SurePath technology. The slides were stained by Papanicolaou method. All cytological diagnosis was correlated with the D&C histological diagnosis.

RESULTS

Cyto-histological correlations were possible in 1672 (89.3%) patients: in 254 (12.8%) patients the D&C was inadequate, in 75 (3.8%) patients the cytology was inadequate, and in 14 (0.7%) patients both were inadequate. In postmenopausal women, 758 of 790 cytologies (96.0%) were adequate, while 586 of 790 histologies (74.2%) were adequate. SAP-1 provided more sufficient materials for cytology than D&C for histology (P < 0.001). Taking atypical hyperplasia or worse as a positive result, the diagnostic accuracy of liquid-based endometrial cytology was 86.1%, sensitivity was estimated at 70.3%, specificity at 88.5%, positive predictive value at 48.0% and negative predictive value at 95.2%. Taking endometrial carcinoma as a positive result, the diagnostic accuracy of liquid-based endometrial cytology was 94.4%; sensitivity was estimated at 53.2%, specificity at 98.6%, positive predictive value at 79.8% and negative predictive value at 95.3%.

CONCLUSIONS

Liquid-based endometrial cytology can be considered a useful method for detecting of endometrial pathology as a first-line approach.

Cytological Characteristics of Endometrial Phasing Using the Specimens Prepared with the Liquid-Based Procedure: Comparison with the Conventional Procedure

OBJECTIVE

To evaluate whether or not the liquid-based procedure (LBP) for endometrial cytology is as worthwhile for endometrial phasing as conventional slides.

MATERIALS AND METHODS

The subjects were 81 women who underwent endometrial cytology and were defined as negative. The specimens obtained by either Endocyte® or Masubuchi aspiration tube® were processed first with the conventional procedure and then with LBP using TACAS™.

RESULTS

(1) The number of subjects diagnosed by the conventional method as having proliferative, mid-, middle-secretory and late-secretory and atrophic phases was 40, 11, 10, 0 and 20, respectively. The rate of agreement with those using LBP was 87.7%. (2) Incidences of large clusters, ductal clusters, palisade arrangement, uneven staining and dirty mucous background detected were significantly higher with the conventional method, whereas with LBP clean background, inconspicuous bonding of cells, scattered solitary glandular cells, clear well-stained cytoplasm and cell compactness were higher. (3) Especially in the proliferative phase, clusters tended to be smaller and lose their architectural structures, and scattered solitary columnar cells were present. (4) Cells in the mid-phase tended to have loose contact and to mimic other phases.

CONCLUSIONS

Cytodiagnosis of endometrial phasing prepared with LBP is feasible to perform when some modifications are implemented.

Combining endometrium sampling device and SurePath preparation to screen for endometrial carcinoma: a validation study

Background:

The aim of this study was to compare specimen adequacy of SAP-1 provided for cytology with that of dilation and curettage (D & C) or hysteroscopy for histology, and evaluate the accuracy of combining endometrium sampling by SAP-1 and liquid-based cytology using SurePath preparation for screening endometrial carcinoma and its precursor.

Methods:

Endometrial specimens from women (n = 1514) with risk factors were obtained using an SAP-1 device for cytological analysis; histological samples were obtained from 375 of these women who underwent D & C or hysteroscopy. Cytological specimens were prepared to liquid-based smear using SurePath technology and stained by Papanicolaou. Histological samples were processed in routine pathology and stained by hematoxylin and eosin.

Results:

Adequate specimens for cytology were obtained from 1458/1541 patients (96.3%), while adequate samples for pathology were obtained from 285/375 patients (76%). However, for postmenopausal women, 1006 of 1045 cytology (86.3%) were adequate, 153 of 238 histology (64.3%) were adequate, it was easier to collect cytological specimens than histological specimens (P < 0.05). The accuracy of endometrial cytology for detecting endometrial carcinoma and its precursor was 92.4% (sensitivity, 73%; specificity, 95.8%; positive predictive value, 75%; and negative predictive value, 95.3%).

Conclusions:

Endometrial cytology using SAP-1 sampling and SurePath preparation may be a reliable approach for screening patients with endometrial carcinoma and its precursor.

Liquid-Based Cytology Preparation Can Improve Cytological Assessment of Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration

OBJECTIVE

This study investigated whether liquid-based cytology (LBC) can improve diagnostic values of cytological assessment of endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA).

STUDY DESIGN

A cohort of 600 cases in West China Hospital was prospectively studied from June 2012 to September 2013. EBUS-TBNA was carried out in outpatients under local anesthesia and moderate sedation. The procedure was performed with an echobronchoscope (BF-UC160F-OL8, Olympus, Tokyo, Japan). Histological cores were stained with hematoxylin and eosin for further study. Additional immunohistological analysis was performed for establishing a reliable diagnosis when necessary. Aspirates were smeared on glass slides and separate aspirates were processed by the monolayer SurePath method.

RESULTS

In total, 480 malignant tumors and 120 benign lesions were confirmed by histological examination. The sensitivity of SurePath liquid-based preparations and conventional smears was 82.1 and 56%, and the specificity was 87.5 and 82.5%, respectively. The combined specificity was 100%. Positive predictive values of the two groups were 96.3 and 92.8%, whereas negative predictive values were 54.9 and 31.9%, respectively. The difference between the two groups was significant (p < 0.001).

CONCLUSIONS

LBC preparation can improve cytological assessment of EBUS-TBNA. Histological study is necessary in cases in which the cytological diagnosis is obscure.

Expression of p53 in imprint smears of endometrial carcinoma

The aims of this study were to determine the expression of p53 protein in endometrial adenocarcinomas (as a potential prognostic indicator before treatment) as well as normal endometrium in imprint smears and to correlate the results with clinicopathologic parameters of primary untreated endometrial cancer patients. Two hundred fifty five patients were evaluated with endometrial imprint cytology during a 29-month period. Endometrial samples freshly resected from women who underwent total abdominal hysterectomy were studied. One hundred twenty six patients had endometrial carcinoma and 129 cases were diagnosed as normal endometrium. The expression of p53 was assessed by immunocytochemistry. Positive staining was correlated with increased surgical-pathological stage, histological grade and lymph node metastases. High expression of p53 staining was significantly more frequent in histological type II than type I endometrial adenocarcinoma. High-grade endometrial carcinoma had higher proportions and stronger intensity compared with low-grade carcinoma. Negative immunostain for p53 protein was found in proliferative, secretory, and atrophic endometrium. Immunocytochemical findings from p53 stain, in addition to cytomorphologic features, appeared to be useful in the diagnosis and in the postoperative prognosis of endometrial carcinoma in endometrial cytology, especially if combined with other markers. High p53 expression correlates with morphologic features of aggressiveness and the expression pattern of p53 correspond to the expected cyclic/atrophic pattern in normal endometrium.

The role of liquid-based preparation in the evaluation of endometrial cytology

OBJECTIVE

Liquid-based preparation (LBP) of the endometrial lesions is an important diagnostic tool for a variety of endometrial abnormalities because of its simplicity and high quali-quantitative diagnostic yield. We aimed to investigate the LBP method for endometrial cytology to evaluate both benign and abnormal endometrial lesions.

STUDY DESIGN

LBP is a semiautomated methodology that has recently become widely available and has gained popularity as a method of collecting and processing both gynecologic and nongynecologic cellular specimens.

RESULTS

Some peculiar endometrial cytoarchitectural features were described using LBPs. These were advantageous to screen as compared to conventional slides due to a smaller screening area and an excellent quality of cell preparations.

CONCLUSIONS

LBP is a useful tool in the cellular diagnosis and follow-up of endometrial abnormalities, which remains complementary to the emerging molecular diagnostic cytopathology. The study of LBPs from endometrial cytology could be challenging since it is affected by numerous look-alikes and diagnostic pitfalls. This review discusses these various entities and takes into consideration the ancillary techniques that may be useful in the diagnostic procedure.

Diagnostic accuracy of liquid-based endometrial cytology in the evaluation of endometrial pathology in postmenopausal women

OBJECTIVE

The aim of this study was to compare liquid-based endometrial cytology with hysteroscopy and endometrial biopsy regarding its diagnostic accuracy in a series of postmenopausal women with abnormal uterine bleeding (AUB) or asymptomatic women with thickened endometrium assessed by transvaginal ultrasound as a screening procedure.

METHODS

  Inclusion criteria were: menopausal status; the presence of AUB and/or thickened endometrium assessed by ultrasound (cut-off 4 mm); a normal Papanicolaou (Pap) smear; and no adnexal pathology at ultrasound. Exclusion criteria were: previous endometrial pathology; and previous operative hysteroscopy. Of 768 postmenopausal women referred to our general gynaecology clinics, 121 fulfilled the inclusion criteria and were recruited to the trial. Twenty-one refused to participate. Cytological sampling was carried out by brushing the uterine cavity using the Endoflower device with no cervical dilation and the vial was processed using a ThinPrep® 2000 automated slide processor. The slides were stained using a Pap method.

RESULTS

  In 98 cases with histological biopsies, endometrial cytology detected five cases of endometrial carcinoma, 10 of atypical hyperplasia and 47 of non-atypical hyperplasia; 36 cases were negative. In two cases cytology was inadequate because of uterine cervical stenosis. Taking atypical hyperplasia or worse as a positive test and outcome, the diagnostic accuracy of the endometrial cytology was 93.5%, with a sensitivity of 92% and specificity of 95%, a positive predictive value of 73% and a negative predictive value of 99%. All the carcinomas were detected by cytology. Only 42% of women with a positive diagnosis were symptomatic. The cytological sampling was well tolerated by all patients. No complication was registered.

CONCLUSIONS

 Liquid-based endometrial cytology can be considered an useful diagnostic method in the detection of endometrial pathology as a first-line approach, particularly if associated with transvaginal ultrasound.

Endometrial glandular and stromal breakdown, Part 4: Cytomorphology of "condensed cluster of stromal cells including a light green body"

This study was undertaken to clarify the origin of the chromophilic substance that stained in light green [light green body (LGB)] was observed in the condensed cluster of stromal cells and in the background of endometrial glandular and stromal breakdown cases. The material consists of cytologic smears of endometrial glandular and stromal breakdown (EGBD) from 58 samples in which a histopathological diagnosis was subsequently obtained by endometrial curettage. The following parameters were examined. (1) The occurrence and number of a LGB. As for the "condensed cluster of stromal cells," "condensed cluster of stromal cells including LGB" and "LBG in background," it was observed with all fields on one slide per case. When it was observed more than one in a preparation, the occurrence was determined and the number was also calculated. (2) Immunostaining of paraffin-embedded tissue sections and cytologic preparations. 1 The occurrence of "condensed cluster of stromal cells," "condensed cluster of stromal cells including LGB" and "LGB in background" was 100%, 44.8% and 91.4%, respectively. The number of "condensed cluster of stromal cells," "condensed cluster of stromal cells including LGB" and "LGB in background" was 21.2, 2.0 and 4.0, respectively. 2 When histological sections from paraffin-embedded tissue were tested by immunocytochemistry, "LGB" stained weakly or negative for fibrinogen, whereas it stained positively for CD31 and factor VIII. In addition, it stained positively for CD42b. 3 When cytologic preparation was tested by immunocytochemistry, "LGB" stained positively for CD31, factor VIII and CD42b. However, as for the fibrinogen, quantitative and qualitative evaluation of the immunocytochemical stain was not feasible due to extensive nonspecific reaction in the whole preparation. The "LGB" in EGBD cases proved to be a thrombus mostly made up by platelets, and it seemed that the recognition of the LGB showed to be a useful cytomorphological criterion for an always more accurate diagnosis of EGBD cases.

Utility of liquid-based cytology in endometrial pathology: diagnosis of endometrial carcinoma

OBJECTIVE

The purpose of this study was to examine the utility of SurePath-liquid-based cytology (LBC) compared to conventional cytological preparations (CCP) in the identification of endometrial carcinoma.

METHODS

During a 13-month period, direct endometrial samples were collected from 120 patients using the Uterobrush. The material comprised 30 cases each of endometrial carcinoma, proliferative endometrium, secretory endometrium and atrophic endometrium. The following points were investigated:(i) the frequency of cell clumps in endometrial carcinoma; (ii) the area of cell nuclei; (iii) overlapping nuclei.

RESULTS

(i) Comparison of the frequency of cell clumps with irregular protrusion pattern and papillo-tubular pattern showed no statistically significant difference in either type of cell clump between CCP and LBC. (ii) Comparison of the nuclear area of cells showed a sequential decrease from endometrial carcinoma to secretory endometrium, to proliferative endometrium and to atrophic endometrium, which was significant in CCP and LBC. (iii) Nuclear area was significantly lower with LBC compared with CCP in endometrial carcinoma, secretory endometrium and proliferative endometrium but not atrophic endometrium. (iv) Comparison of the degree of overlapping nuclei showed a sequential decrease from endometrial carcinoma to proliferative endometrium, to secretory endometrium and to atrophic endometrium, which was significant in both CCP and LBC. (v) Comparison of the degree of overlapping nuclei between CCP and LBC showed no significant difference for normal types of endometrium, but LBC had significantly higher values (P < 0.0001) in endometrial carcinoma than in CCP.

CONCLUSIONS

The results of this study revealed that applying diagnostic criteria used in CCP to LBC was easy to achieve, because LBC had excellent cytoarchitectural preservation and cells were well presented. Although we have not examined all cytological features of malignancy and have not considered atypical hyperplasia, we believe that this method may be a useful tool in the diagnosis of endometrial cytology.

New diagnostic reporting format for endometrial cytology based on cytoarchitectural criteria

OBJECTIVE

The aim of this study was to develop a new reporting format for endometrial cytology that would standardize the diagnostic criteria and the terminology used for reporting.

METHODS

In previous studies, cytoarchitectural criteria were found to be useful for the cytological assessment of endometrial lesions. To apply these criteria, an appropriate cytological specimen is imperative. In this article, the requirements of an adequate endometrial cytological specimen for the new diagnostic criteria are first discussed. Then, the diagnostic criteria, standardized on a combination of conventional and cytoarchitectural criteria, are presented. Third, terminology that could be used, not only for reporting the histopathological diagnosis, but also for providing better guidance for the gynaecologist to determine further clinical action, is introduced. The proposed reporting format was investigated using endometrial cytology of 58 cases that were cytologically underestimated or overestimated compared to the histopathological diagnosis made on the subsequent endometrial biopsy or surgical specimens.

RESULTS

Of the 58 cases, 12 were reassessed as being unsatisfactory for evaluation. Among the remaining 46 cases, 25 of the 27 cases, which had been underestimated and subsequently diagnosed as having endometrial carcinoma or a precursor stage on histopathological examination,were reassessed as recommended for endometrial biopsy. On the other hand, 19 cases overestimated by cytology were all reassessed as not requiring biopsy.

CONCLUSIONS

The reporting format for endometrial cytology proposed in this article may improve diagnostic accuracy and reduce the number of patients managed inappropriately.