Gastric-type adenocarcinoma of the cervix masquerading as serous endometrial carcinoma: a diagnostic pitfall
Elham Shirali, Fariba Yarandi, Soheila Sarmadi, Behnaz Moradi, Azad Tavakoli, Sara RamhormozianIntroduction and importance:
Gastric-type adenocarcinoma (GAC) of the cervix is a rare, aggressive, human papillomavirus (HPV)-independent subtype of endocervical adenocarcinoma that can closely resemble other high-grade gynecologic malignancies, particularly serous endometrial carcinoma. Accurate diagnosis is essential because GAC is associated with adverse outcomes and can be difficult to classify when it extends into the lower uterine segment.
Presentation of case:
A 67-year-old postmenopausal woman presented with abnormal vaginal bleeding and a diffusely enlarged cervix. Endometrial sampling initially suggested high-grade serous carcinoma arising in an endometrial polyp, while magnetic resonance imaging demonstrated a 5.5-cm mass centered in the cervix with lower uterine segment extension and no radiologic lymphadenopathy. She underwent a type II modified radical hysterectomy with bilateral salpingo-oophorectomy, omentectomy, and pelvic lymph-node dissection. Final pathology showed a 6-cm HPV-independent GAC involving all four cervical quadrants, with 15-mm deep stromal invasion, focal lymphovascular space invasion, perineural invasion, and lower uterine segment extension; parametria and vaginal cuff were uninvolved, and the paracervical margin was negative but <1 mm. Two pelvic lymph nodes were negative. The tumor was high-risk HPV negative, p16 focally positive (non-block), PAX8 diffusely positive, p53 wild-type, ER diffusely positive, PR negative, and MMR proficient. MUC6 and HIK1083 were unavailable. The tumor was classified as FIGO 2018 stage IB3. Postoperative concurrent chemoradiotherapy was initiated 4 weeks after surgery without a brachytherapy boost. At 14 months after surgery, the patient remained disease-free.
Clinical discussion:
This case illustrates a diagnostic pitfall in which cervical GAC mimicked serous endometrial carcinoma because of lower uterine segment involvement, papillary high-grade morphology, and an endometrial polyp. The cervical epicenter, barrel-shaped enlargement, deep cervical stromal invasion, HPV negativity, focal/non-block p16 expression, wild-type p53 pattern, and integrated histologic review supported a cervical gastric-type primary. Gastric differentiation markers are useful supportive tests when available, but MUC6 and HIK1083 were not available in this case, and this limitation is explicitly acknowledged.
Conclusion:
GAC of the cervix is a rare HPV-independent malignancy in which accurate localization of the primary site is as important as immunophenotypic interpretation. Careful correlation of gross findings, imaging, histology, HPV status, and immunohistochemistry can prevent misdiagnosis as serous endometrial carcinoma and guide multidisciplinary treatment.