Rare malignant ovarian tumors: a review

There are many histologic types of gynecologic malignancies. I reviewed three rare ovarian tumor types that have poor prognoses. Ovarian mesonephric-like adenocarcinoma (MLA) is a newly described histological type known for its aggressive behavior. It is thought to arise from mesonephric duct remnants of the female genital tract and is typically associated with endometriosis. Although MLA has some similarities to endometrioid carcinoma, they have different prognoses. Recurrence of MLA is common, even in early stage cases, and distant metastases, especially in the lungs, are often seen. MLA is characterized by positive immunohistochemical-staining for TTF-1, GATA3, PAX2, and CD10, and negative staining for estrogen and progesterone receptors. Data on treatment for MLA are scarce, and further studies are needed. Adult granulosa cell tumors, the most common type of malignant ovarian sex cord-stromal tumors, have an indolent growth pattern. Chemotherapy, hormone therapy, and radiotherapy have all shown some efficacy. However, debulking surgery remains the most important treatment because tumor disruption or remnants are risk factors for recurrence. Late recurrence is also characteristic of this tumor. Malignant transformations of mature teratoma are suspected when the patient is relatively old and the tumor is large. Squamous cell carcinoma is the most common somatic malignancy. Treatment must be tailored to the transformed histology. Chemotherapy and radiation have shown some efficacy; however, the prognosis is extremely poor in advanced cases. Because these three types of ovarian tumors are rare, research on possible treatments has been difficult, but recent significant advances in drug therapy are expected to lead to the development of effective treatments.