This is an example of an atrophic pattern. Although atrophy may mimic syncytical HSIL due to the presence of highly cellular clusters in both, the cells in atrophy lack HSIL features, such as hyperchromatic and irregular nuclei, coarse chromatin, and nuclear disarray and overlapping. In atrophy, the cellular components are mainly basal squamous cells and parabasal squamous cells.
Atrophy is unrelated to HPV infection.
Estrogen replacement promotes squamous maturation, resulting in a reduced number of basal and parabasallike cells and an increased number of intermediate and superficial squamous cells.
In cases in which it is difficult to distinguish between atrophy and a high grade intraepithelial lesion in an atrophic background, Ki-67 and p16 immunostains may be helpful. The Ki-67 stain will show increased mitotic activity going up into the intermediate and superficial layers in HSIL. p16 typically is diffusely positive in HSIL, but not in atrophy.
In cases in which it is difficult to distinguish between atrophy and a high grade intraepithelial lesion, treating the patient with topical estrogen may promote the maturation of atrophic squamous cells, while true high grade intraepithelial lesion cells will not be affected. The latter will persist in a background of mature squamous cells on a follow-up cervicovaginal cytology test.
