Primary ovarian fibrosarcoma. Report of an unusual neoplasm

Introduction: Ovarian fibrosarcoma is an extremely rare malignant ovarian stromal tumor, with few cases reported in the literature. Main symptoms and/or clinical findings: A 56-year-old posmenopausal woman with scant vagi-nal bleeding of several days' duration and pain in the right iliac fossa without fever or digestive symptoms. The gynecological examination was normal. Main diagnoses, therapeutic interventions and results: Transvaginal ultrasound showed a homogeneous endometrium, a 2.4 x 1 cm myoma, and a heterogeneous solid-cystic lesion with thick septa measuring 6.4 x 6.8 cm in the left ovary. An intraoperative histological study was performed, which was reported as: solid neoplasm suspicious of malignancy. Hysterectomy plus double adnexectomy, omentectomy, and lymphadenectomy were performed. Histologically, the neoplasm was made up of spindle cells arranged in sheets and intertwined fascicles with a diffuse spike-like appearance, with moderate nuclear atypia, areas of necrosis and hemorrhage foci; 12 mitoses were identified for every 10 high-power fields. Immunohistochemically the cells were positive for inhibin, actin 1A4, vimentin, calretinin, CD56 and CD99. The proliferative rate with Ki-67 was 25%. The definitive diagnosis was: primary ovarian fibrosarcoma. One year later, the patient is free of the disease without any adjuvant treatment and continues to be followed up.Conclusion: Ovarian fibrosarcoma is an exceptional malignancy with a poor prognosis. Currently, the treatments and prognostic factors for ovarian fibrosarcoma are still the subject of debate. This case highlights the important role of the intraoperative study and immunohistochemistry for its correct diagnosis.& COPY; 2023 Elsevier Espana, S.L.U. All rights reserved.