Utility of thin-layer preparations in the endometrial cytology

Abstract

The purpose of the current study was to examine the use of thin-layer cytologic (TLC) preparation compared to conventional cytologic preparation (CCP) in the normal endometrium (proliferative, secretory, atrophic) and endometrial glandular and stromal breakdown (EGBD). During a 6-month period, we compiled 158 cases by collecting a direct endometrial sample using the Uterobrush. The material comprised 40 cases of proliferative endometrium, 42 cases of secretory endometrium, 46 cases of atrophic endometrium, and 30 cases of EGBD. The following points were investigated: (1) number of endometrial epithelial cell clumps; (2) presence of TLC > CCP cases on number of epithelial cell clumps; (3) number of condensed cluster of stromal cells; (4) presence of TLC > CCP cases on number of condensed cluster of stromal cells; (5) presence of metaplastic clumps with irregular protrusion-containing condensed stromal cluster; (6) presence of a clear background; (7) presence of blood vessel in TLC; (8) presence of blood vessel of length more than diameter of a field in object ×20 glasses in TLC. (1) In all phases, the number of epithelial cell clumps per a unit area of a preparation of TLC is greater than in CCP. (2) Cells (condensed cluster of stromal cells and metaplastic clumps with irregular protrusion-containing condensed stromal cluster) of useful and adequate numbers for a diagnosis of EGBD were observed in TLC. (3) In all phases, TLC was significantly higher than CCP on the appearance of a clear background. (4) The proliferative endometrium and secretory endometrium were highly significant in comparison with atrophic endometrium and EGBD, respectively, in terms of the occurrence of a blood vessel of length more than diameter of a field in object ×20 glasses. Although the preparation area of TLC is smaller than that of CCP, the preparation has a clean background so that an accurate report on the patient's condition is possible. Therefore, TLC preparation is a useful tool for the accurate and reliable diagnosis of normal endometrial phase and EGBD, because the preparation area is confined and identification of the target cell clumps is easy.

Introduction

Population-based cancer data in Western countries, particularly the United States, have shown a significant increase in the incidence of endometrial cancer starting in the early 1970s. It is also known that endometrial cancer has risen each year in Japan over a period of 30 years. In Japan, since the health insurance law for the elderly was passed in 1987, the initial method to detect endometrial cancer has used cytologic examination. The rate of its application in all cases of endometrial cancer has risen from 10% in 1983 to 45% in 2004 [1]. Thus, the value of endometrial cytology in assessing endometrial abnormalities has been shown and is widely accepted for screening in Japan [2].

One of the aims of endometrial cytology is to detect endometrial hyperplasia because of its supposed role as a precursor of endometrial carcinoma. Therefore, an accurate determination of each normal endometrial phase (proliferative, secretory, atrophy) is important. In addition, endometrium of anovulatory dysfunctional uterine bleeding causes may simulate endometrial adenocarcinoma and its precursors, leading to difficulty in cellular interpretation [3], [4], [5], [6], [7], [8]. Therefore, the accurate diagnosis of endometrium in anovulatory dysfunctional uterine bleeding cases is also necessary.

The advent of liquid-based cytology provides a platform for the detection and evaluation of cervical cellular abnormalities. The main advantages of this technique are reduction of the number of inadequate smears and provision of enough cells for the detection of infectious agents such as human papillomavirus. Several investigations have suggested that liquid-based cytology may achieve a diagnostic sensitivity as high as that found in conventional preparations [9], [10], [11], [12], [13], [14]. Moreover, it is well known that the method of liquid-based cytology has been approved for use in the United States by the US Food and Drug Administration in 1996 as a technique for cervical carcinoma screening, and with known established advantages over conventional cytology in nearly all cellular samples [9], [10], [11], [12], [13], [14].

Recently, we have described the cytologic assessment of endometrial lesions (including normal endometrium, endometrial hyperplasia, well-differentiated adenocarcinoma, and disordered endometrium associated with anovulation—the so-called endometrial glandular and stromal breakdown [EGBD]) by using cytoarchitectural criteria [15], [16], [17]. However, those studies were evaluated via direct smear preparation for conventional cytology. Only a few studies have been found in the literature for endometrial lesions in conjunction with liquid-based cytology, because—except for Japan—the method is not well known in other countries [18], [19], [20], [21]. The objective of this study was to assess the use of liquid-based cytology compared to conventional cytology in the evaluation of women presenting with normal endometrium and EGBD.