INTRODUCTION
Endometrial cancer is the second common tumor in the female reproductive
system worldwide with an increasing mortality due to the epidemic of
obesity and the resulting hyperinsulinemia (1, 2). The early detection
of this cancer and precancerous change plays an important role in
reducing mortality and improving survival rate. In recent years,
endometrial cytology test has become a new direction in the screening of
endometrial cancer and precancerous change due to low trauma, convenient
operation, economic efficiency, and high safety (3).The common devices
to collect endometrial cells contain Li Brush, SAP-1, Pippelle, Tao
Brush, and so on (4, 5).
Haematoxylin and eosin (H-E) stain is the most basic and widely
pathological method used in cytological and histological diagnosis. It
can be used to visualize the cellular morphology and structures of
different composition excellently, especially in differentiating nucleus
from cytoplasm, even if under low magnification (6-8). Hematoxylin is a
basophilic dye that turns cell nucleus into blue-purple, and eosin is an
acidic dye that turns cell cytoplasm, collagen, and erythrocytes into
red-pink (9). The two dyes are combined in sequence for abundant
contrast between the cellular components (10, 11). H-E stain is easily
implemented, inexpensive, reliable and informative (12).This stained
slides can be kept many years without fading due to its better stability
(8). However, it is difficult to differentiate amyloid, muscle, keratin
and other extracellular and intracellular secretions which are all
eosinophilic (13).
Papanicolaou stain is commonly used in identification of cytological
smears, which improves the visualization of nuclear and cytoplasmic
morphology (12, 14, 15). It can assess pivotal cellular features,
including nuclear chromatin alterations, cytoplasmic structures,
especially in maturing squamous epithelial cells. Papanicolaou stain is
also performed in detecting the degrees of cellular degeneration or
necrosis, and the production of mucin, glycogen, and keratin (14, 16,
17). In recent studies, Papanicolaou stain has been confirmed validly
and widely in the detection of cervical cells (18, 19).Though this
method was not originally designed for endometrial cancer, some
researchers tried to modify this stain to improve the detective rate of
endometrial lesions (20). The disadvantages of Papanicolaou stain
contain time-consuming, complicated procedure and additional wet
fixation (21, 22).
Although both methods could be applied to staining endometrial cells
(23-25), no research was published to compare the effects. In this
study, we distinguished the difference between H-E and Papanicolaou
stain through the semi-quantitative scoring system in endometrial
cytology ( Table S1) (24).