RESUMO
Fibromatous tumors of the ovary are considered to originate from specialized ovarianstromal cells and account for approximately 4% of all ovarian neoplasms. Most ovarianfibromatous tumors are benign, but infrequently there are histologically malignant appearances.Malignant fibromatous tumor can be categorized into two separate types of tumorsrelating to prognosis, cellular fibroma and fibrosarcoma. The cellular fibroma has one tothree mitotic counts per 10 high power fields(HPF). Unless an adhesion or rupture appearson this tumor, recurrence should not happen after operation. Furthermore, where themitotic count per 10 HPF is over four, it is classified as a very bad fibrosarcoma case interms of prognosis.We have met a case of large ovarian fibrosarcoma with has ten mitotic counts per10 HPF. We hereby report this case with the brief review of literatures.