A unique fibrous tumor of the ovary: fibrosarcoma or mitotically active cellular fibroma?

A unique fibrous tumor of the ovary is reported. A 32-year-old nulliparous woman was diagnosed with a left ovarian tumor and underwent left salpingo-oophorectomy. Macroscopically, the cut surface of the tumor showed yellowish multilobular areas. There was no sign of necrosis or hemorrhage within the tumor. Microscopically, the tumor consisted of two well-circumscribed components. One corresponded to the yellowish lobular areas; there were more than 10 mitotic figures per 10 high-power fields and strong staining for Ki-67, suggesting fibrosarcoma, but nuclear atypia was not severe. In the other component, there were few if any mitotic figures; there was no nuclear atypia and marked cellularity. Pathologically, the tumor was considered a variant fibrosarcoma or a mitotically active cellular fibroma. In light of these pathological findings along with the patient's age and obstetrical history, no further treatment was performed. There has been no evidence of recurrence after 1-year follow-up.