Clear cell adenocarcinoma of the cervix in a perimenopausal woman: a case report and immunohistochemical study

We report a rare case of sporadic cervical clear cell adenocarcinoma (CCAC) in a 46-year-old perimenopausal woman without the classic risk factors of in utero diethylstilbestrol (DES) exposure or high-risk human papillomavirus (HPV) infection, who presented with abnormal vaginal bleeding. Imaging revealed a bulky, barrel-shaped cervix with a large mass (measuring 4.8 × 6.7 × 3.1 cm), classified as FIGO stage IB3 based on pelvic examination and imaging findings. The patient underwent radical surgery, and the diagnosis was confirmed histologically and supported by a definitive immunohistochemical profile: the tumor was positive for PAX-8 and napsin-A, showed only partial positivity for p16, and exhibited a high Ki-67 index (70%), consistent with an HPV-independent clear cell carcinoma. This case underscores the sporadic, HPV-independent form of CCAC and highlights the critical role of immunohistochemistry in establishing the diagnosis, particularly in clinically atypical presentations.