Recurrent Mesonephric-like Adenocarcinoma of the Ovary with Bladder and Vaginal Recurrences: A Diagnostic Challenge

Background and Clinical Significance: Mesonephric-like adenocarcinoma (MLA) of the ovary is a very rare entity that has only recently been recognized as a distinct subtype in the World Health Organization (WHO) classification. It is an aggressive tumor with a propensity for recurrence. The aim of this case report was to highlight the diagnostic challenges associated with MLA and the importance of immunohistochemical and molecular testing. Case Presentation: We report the case of a 59-year-old woman who presented with a left ovarian tumor. Histopathological examination led to an initial diagnosis of low-grade serous carcinoma, and the patient was treated accordingly. Five years later, the tumor recurred in the bladder wall and was initially interpreted as urothelial carcinoma. One year later, a further recurrence was identified at the vaginal cuff. Integrated review of the original ovarian tumor and recurrent lesions, together with immunohistochemical and molecular findings, supported the diagnosis of ovarian MLA with bladder and vaginal recurrences. Conclusions: Ovarian MLA is extremely rare and can mimic more common ovarian carcinoma subtypes. Awareness of its morphological and immunohistochemical features is essential to avoid misdiagnosis. MLA should be considered in recurrent gynecologic tumors with mesonephric morphology/immunophenotype even when the recurrence occurs in an unusual site such as the bladder and mimics a primary urinary malignancy.