Objective: Wilms tumor gene product, a tumor suppressor gene, now is considered to have oncogenic functions. There seems to be differences in WT1 expression among surface epithelial ovarian tumor subtypes. Method: Immunohistochemistry for WT1 was done on 35 serous & 3 mucinous cystadenocarcinomas, 9 borderline serous & 10 borderline mucinous tumors, 7 endometrioid ovarian carcinomas, 3 clear cell carcinomas, 1 malignant Brenner tumor, 2 metastatic adenocarcinomas and 6 endometrial adenocarcinomas. A tumor was considered negative if<1 % of tumor cells were stained. Positive reactions were graded :1+,1-24 %; 2+,25-49 %; 3+,50-74 %; 4+,75-100 %. Results: Of serous cystadenocarcinomaes, 30(85.7 %) were positive,4 showed reactivity of<50 % of the tumor cells and one were negative. All borderline serous tumors were positive. All mucinous tumors, endometrioid carcinomas, clear cell carcinomas, metastatic adenocarcinomas and primary endometrial carcinomas were negative. The single malignant Brenner tumor were positive for WT1. Conclusion: WT1 is a good marker to distinguish primary ovarian serous carcinomas from other surface epithelial tumors (especially endometrioid subtype) and metastatic carcinomas (especially endometrial serous carcinoma), other than malignant mesothelioma. Degree of expression is not an indicator to separate high grade borderline serous tumors from low grade ones. Objective: FATWO is a rare neoplasm originating from the mesonephric duct remnants that occurs predominantly in the broad ligament but also in the ovary. It is considered a lowmalignant potential tumor. However local recurrences and metastases have been reported. Method: A 45 year-old female, on routine gynecological physical examination, followed by pelvic ultrasonography and computer tomography was diagnosed with a mass at the right ovary. A salpingo-oopherectomy was performed. On gross examination a well-circumscribed, solid and focally cystic tumor measuring 10,5×7×5,5 cm arose in the ovarian hilus. Results: Microscopically the tumor consisted of mediumsized, ovoid to polygonal cells arranged in a solid, tubular and sieve-like pattern. Some cystic spaces were lined by low-cuboidal cells and contained amorphous, eosinophilic material. Cellular atypia and mitoses were rare. The tumor cells were positive for Vimentin, Inhibin-a (focally), CD10, cytokeratins 8/18, 19 and 7 (focally) and negative for cytokeratin 20, epithelial membrane antigen, carcinoembryonic antigen and a-fetoprotein. Conclusion: Histopathological and imunohistochemical findings consistent with an ovarian FATWO. Differential diagnosis includes endometrioid carcinoma, clear-cell carcinoma, Sertoli-Leydig cell tumors (retiform variant) and rete ovarii adenoma. Surgical excision is the optimal treatment. Radiation therapy, chemotherapy or even targeting molecular therapy is questionable. Müllerian adenosarcoma is a rare mixed tumor of low malignant potential. Usually presented as a large endometrial polyp in postmenopausal women. They are associated with tamoxifen or radiation therapy. Microscopy shows a mixture of benign glandular epithelium and low-grade endometrial sarcoma is typically concentrated around the glands. The differential diagnosis is made with the adenofibroma, but now is doubted the existence of this tumor and is considered more of a distinct adenosarcoma. The treatment is total hysterectomy. Sisters of 24 and 16 years with a history of dysmenorrhea. Hysteroscopy was performed to the eldest one, in which multiple polyps are observed and partially resected. The pathological diagnosis was Mixed Mullerian tumor, adenofibroma/adenosarcoma. Total abdominal hysterectomy was performed. Histological examination showed a mixed tumor with glandular component and a low-grade sarcomatous, scarce mitosis, mild atypia and no necrosis. The diagnosis was: mullerian adenosarcoma. A year later, a hysteroscopy and endometrial biopsy was performed to the youngest sister, that showed endometrial polyps with stromal predominance, and no significant atypia. With the diagnosis of mullerian adenosarcoma, and taking into account family history, total hysterectomy was performed. Adenosarcoma is a rare tumor whose family presentation is not described in the literature.