Interpretation
Although there was a statistical difference in cytoplasmic details between H-E and Papanicolaou stain in endometrial cells, the grade of cytoplasmic details was unsatisfied, as well as nuclear details. The methods might cause the breakdown of DNA and RNA and affect the nucleic acid structure in the cell nucleus (39). Some studies suggested that H-E and Papanicolaou stain led to a decrease in DNA recovery, with a degree of DNA breakage compared to unstained samples (39, 40). The pre-analytical variables that affect DNA of cytological samples include specimen collection and processing, properties of cells, cytological substrate type, fixative, and extraction method (41). Hematoxylin is used in both methods, which is a Polymerase Chain Reaction inhibitor. It can stain the nucleus and induce mRNA fragmentation (39). Therefore, it remains to be investigated whether reducing the dosage of Hematoxylin can improve the grade of nuclear details and thus affect the morphological characterization of endometrial cells.
Some patients in the study showed negative histologic results but malignant cells in cytology (false positive). It is considered to be related to patient’s thin endometrium which is difficult to be scraped. In clinic, as for women with postmenopausal vaginal bleeding and thin endometrial suggested by ultrasound, tissue sampling is more difficult due to atrophy of cervix and uterine as well as adhesion of cervical canal. The amount of endometrium that can be extracted is less, and the failure rate of histological diagnosis is high. Therefore it is easy to be misdiagnosed (42). Detecting endometrial cells by Li Brush is a better supplement to histological results (43). However, some patients showed atypical hyperplasia or endometrial cancer in histology but negative results in cytology (false negative). The reasons probably include the following: (1) bias caused by staining method itself; (2) bias caused by wrong operation process; (3) insufficient sampling of endometrial cells (42). In practice, process and operation should be strictly standardized to reduce the occurrence of bias.
In the following study, endometrial cancer will be subdivided into different pathological patterns through a large sample multi-center study. The different combination of endometrium will be analyzed and compared respectively. The improved measures were in order to further demonstrate that H-E stain might be better than Papanicolaou stain in endometrial cytology.