Female adnexal tumors of Wolffian origin (FATWOs) are rare tumors arising in the leaves of the broad ligament from the remnants of the mesonephric duct. Most FATWOs behave in a benign fashion, and there are only 11 cases reported in the literature showing malignant FATWOs. In this study, the authors report a 50-year-old woman with a malignant FATWO, positive for calretinin, CD34, CD56, focal positive for CK, and CD117 (c-Kit). The tumor cells were negative for alpha-inhibin, actin, S-100, CK 19, and EMA. The tumor showed a high mitotic count (17/10HPF), necrosis, capsular invasion, high cellularity, and moderate cytologic atypia. Review of literature showed that about 10% of FATWOs pursued an aggressive course and were generally regarded to be at least low malignant potential. Adverse prognosis factors include large side, capsular invasion and rupture, hypercellularity, nuclear pleomorphism, and increased mitotic activity. Because of the few reported cases, there are no clear recommendations regarding initial evaluation, treatment, and follow-up. A larger retrospective study is needed to support to establish diagnostic criteria and the scale of malignant potential.