Utility of thin-layer preparations in the endometrial cytology: evaluation of benign endometrial lesions

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 x20 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 x20 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.