A malignant steroid cell tumor of the ovary presenting as advanced abdominal malignancy

Ovarian Steroid Cell Tumors (SCTs), Not Otherwise Specified (NOS), are exceedingly rare sex cord-stromal neoplasms. While often hormonally active and diagnosed at an early stage, they can present with aggressive features and mimic advanced epithelial ovarian carcinoma (EOC), posing significant diagnostic and therapeutic challenges. A 58-year-old postmenopausal woman with a complex cardiac history presented with abdominal pain and a palpable mass. Imaging revealed a large, complex right adnexal mass measuring 22 cm with ascites, peritoneal seeding, and lymphadenopathy, highly suggestive of advanced EOC. Tumor markers showed elevated CA-125 (533 U/mL) and LDH (792 U/L). She underwent primary cytoreductive surgery, including total hysterectomy, bilateral salpingo-oophorectomy, omentectomy, and right hemicolectomy due to extensive bowel involvement. Histopathology and immunohistochemistry (Inhibin+, Calretinin+, PAX8−, CK7−) confirmed a diagnosis of a malignant steroid cell tumor, NOS, FIGO stage IIIC. This case underscores the critical importance of considering rare ovarian stromal tumors in the differential diagnosis of apparent advanced ovarian cancer, especially in the absence of significant hormone-related symptoms. It highlights the diagnostic role of immunohistochemistry and the pivotal need for complete surgical cytoreduction, as these tumors are largely chemoresistant. This report adds to the sparse literature on the management of advanced-stage malignant SCTs.