[Pitfalls in diagnosing female genital tract: ovarian disease].

Because the ovaries are composed of surface epithelial cells, germ cells, sex-cord stromal cells and stroma, tumors of various histopathologies arise from this organ. In addition, a number of non-tumorous diseases form adnexal masses such as endometriosis and tubo-ovarian abscess. Furthermore, tumors arising from other pelvic organs are sometimes mis-diagnosed as ovarian tumors. Therefore, it is difficult to predict the histological type of an adnexal mass prior to surgery even though the MR characteristics of various ovarian tumors have been reported. Because of the large number of patients, there are two 'common sense' considerations in diagnosing female intrapelvic masses in daily practice: 1) solid adnexal masses are malignant ovarian tumors, 2) predominantly cystic intrapelvic masses originate from the ovaries. However, certain tumors do not conform to common sense. For example, fibrothecomas and benign teratomas are exceptions to 1), and subserosal pedunculated leiomyomas and cystic adenomyosis are exceptions to 2). The MR characteristics, pitfalls to diagnosis, and clues to correct imaging diagnosis are discussed in this review.