In patients with the above findings in the Pap test, the interpretation of pregnancy-related changes becomes straightforward when the history of a positive pregnancy test and the HR-HPV test is negative. However, the lack of clinical history can make the interpretation challenging as decidual cells can raise the differential diagnoses of atypical squamous or glandular cells. Decidual cells may exhibit some degree of nuclear atypia with high N/C ratio that could lead to an erroneous interpretation of a high-grade squamous intraepithelial lesion. Typical changes of dysplastic squamous cells (koilocytic changes, irregular nucleic contours, and hyperchromasia) are not present. The single-cell pattern in the ThinPrep material can be reminiscent of metaplastic cells. In that case, the lack of cytoplasm may be interpreted as worrisome for high-grade dysplasia (atypical squamous cells cannot rule out high-grade). It is likely that high-grade squamous intraepithelial lesion with metaplastic features can be a major differential diagnosis (Figure 4). The differential diagnosis of a glandular lesion, especially in women in their 40s and 50s, can be raised when decidual cells are present in groups. However, it should be noted that decidual cells still maintain their polarity, do not significantly overlap and often retain abundant cytoplasm. Hyperchromatic crowded groups representative of high-grade dysplasia usually have dark, coarse chromatin with scant cytoplasm. For comparison, please see Figures 5 A-B of high-grade squamous intraepithelial lesion and atypical glandular cells, favor neoplastic endocervical cells, respectively. The subsequent biopsy showed both high-grade squamous intraepithelial lesions and adenocarcinoma in situ (Figure 6A). Immunohistochemistry shows strong band-like (nuclear and cytoplasmic staining for p16), which is the typical pattern for cervical HPV-associated neoplasia (Figure 6B).