Stage IA Ovarian Cancer With an Anaplastic Carcinomatous Mural Nodule in a Mucinous Cystadenoma: A Case Report

Anaplastic carcinomatous mural nodules in ovarian mucinous tumors are rare and can be difficult to distinguish from sarcoma-like or sarcomatous nodules.We report a 66-year-old woman who presented with abdominal distension and a mass extending to just below the xiphoid process.Magnetic resonance imaging revealed a 304 × 260 × 126 mm cystic abdominopelvic tumor with a solid component showing diffusion restriction.Serum cancer antigen 125 was elevated to 173 U/mL.Laparotomy was performed, and the tumor was removed after aspiration of its cystic contents without intraperitoneal spillage.Total hysterectomy, bilateral salpingo-oophorectomy, pelvic and para-aortic lymphadenectomy, and partial omentectomy were performed, with no residual tumor.Histopathological examination revealed a benign mucinous cystadenoma with an anaplastic carcinomatous mural nodule composed of spindle cells and giant cells.Immunohistochemistry showed focal AE1/AE3 positivity and positive Ki-67 and p53 staining.Peritoneal washing cytology was negative, and no lymph node metastases were identified.The tumor was classified as International Federation of Gynecology and Obstetrics stage IA (pT1aN0M0).Postoperative surveillance without adjuvant chemotherapy was selected after discussion with the patient, considering the complete resection and uncertain benefit of adjuvant chemotherapy in this setting.The patient remained alive without evidence of disease 54 months after surgery.This case provides additional long-term clinical follow-up for anaplastic carcinoma associated with a benign mucinous epithelial component.