Supplementary Material for: Gastric-Type Endocervical Adenocarcinoma Mimicking Advanced Ovarian Carcinoma: A Diagnostic Challenge with Carcinomatosis and Obstructive Uropathy

Introduction Gastric-type endocervical adenocarcinoma (GTEC) is an uncommon and aggressive variant of endocervical adenocarcinoma, notable for its lack of association with human papillomavirus (HPV). It often presents late in its clinical course, leading to diagnostic challenges as it may mimic other gynecologic malignancies. Case Presentation This case report details the clinical course of a 63-year-old female patient who presented with a two-month history of lower abdominal pain, abdominal distention, constipation, and post-coital bleeding. These symptoms are atypical for GTEC, in which patients typically experience a mucus-like or watery vaginal discharge. A comprehensive diagnostic workup revealed elevated serum levels of Cancer Antigen (CA) 125 and CA 19-9. Cervical and vaginal biopsies subsequently confirmed a diagnosis of moderately differentiated adenocarcinoma, supported by immunohistochemical analysis that demonstrated strong positivity for CK7, CEA31, HIK1083, and HNF1-β, while showing negativity for p16, estrogen receptor (ER), and p53. Despite her relatively short symptomatic clinical course, the patient exhibited signs of advanced disease, characterized by peritoneal carcinomatosis, vaginal involvement, and obstructive uropathy from pelvic mass effect. Conclusion This patient's atypical clinical presentation illustrates that GTEC may mimic ovarian-like tumors, resulting in misclassification and diagnostic delay, and further underscoring the challenge that HPV-independent tumors such as GTEC pose to current screening strategies and diagnostic frameworks.