Benign hemorrhagic mesenteric cyst mimicking peritoneal dissemination in early-stage ovarian clear cell carcinoma: a case report

BACKGROUND: Ovarian clear cell carcinoma (OCCC) is a distinct subtype of epithelial ovarian cancer with characteristic biological behavior and clinical features. Accurate preoperative staging is essential for guiding optimal management; however, imaging findings may occasionally be misleading. CASE PRESENTATION: We report the case of a 58-year-old postmenopausal woman with OCCC who was clinically suspected to have advanced disease because of a large abdominopelvic tumor, mesenteric abnormalities on contrast-enhanced CT, and an elevated serum CA125 level. These findings raised concern for peritoneal dissemination and extraovarian involvement. However, intraoperative exploration identified a discrete hemorrhagic lesion within the mesentery rather than diffuse malignant seeding. Final histopathological examination confirmed early-stage OCCC, while the mesenteric lesion was identified as a benign hemorrhagic cyst. At the most recent clinical evaluation, 12 months after surgery, the patient remained disease-free. CONCLUSIONS: This case highlights a potential diagnostic pitfall in which benign extraovarian lesions may mimic metastatic disease, potentially leading to overstaging. It underscores the importance of integrating imaging findings with intraoperative evaluation and histopathological confirmation to ensure accurate staging and appropriate clinical management.