Abstract
Background: The Arias-Stella reaction is a hormone-related atypical endometrial change characterized by hypertrophy and vacuolization of glandular epithelial cells, associated with marked nuclear pleomorphism, enlargement, and hyperchromasia. When presenting in extra-uterine sites, the differentiation of Arias-Stella changes from other more ominous clear cell lesions may pose significant difficulties.
Case Report: We report a case of an endocervical clear cell lesion incidentally discovered during a prenatal visit of a young pregnant woman. Interpretation of the pathological findings was complicated by the small size and fragmentation of the specimen.
Conclusions: Recognition of Arias-Stella reaction in extra-uterine sites, especially in young women, is critical to avoid misdiagnosis of this innocuous lesion as clear cell adenocarcinoma. Attention to cellular and nuclear detail, as well as careful consideration of the clinical scenario, is crucial for establishment of the correct diagnosis.

Keywords: clear cell carcinoma, endocervix, Arias-Stella