RESUMO
Background: Uterine leiomyomas are benign tumors characterized by pelvic pain and abnormal bleeding. Their evolution can lead to degenerative changes, occasionally mimicking malignancies on imaging, presenting diagnostic challenges. Case presentation: A 31-year-old nulliparous woman presented with symptoms of bloating, cramping, and abdominal distension. Imaging suggested an advanced ovarian malignancy, showing a complex adnexal mass and elevated CA-125 levels. During exploratory laparotomy, what was suspected to be ovarian cancer was instead identified as a large uterine mass on pathologic evaluation revealing a benign leiomyoma with extensive hydropic change. Conclusion: This case highlights the diagnostic intricacies associated with large complex adnexal masses and illustrates how benign conditions like leiomyomas with hydropic degeneration can mimic ovarian cancer. This emphasizes the importance of comprehensive preoperative and intraoperative assessments to tailor management and avoid unindicated radical procedures.