The excellent resolution provided by transvaginal sonography allows characterization of many ovarian masses. Certain features of an ovarian mass can suggest that the tumor is malignant. According to a study by Brown et al, the solid component of a malignant mass is usually nonhyperechoic (1). However, benign masses may have a nonhyperechoic solid component (32%) or a “markedly hyperechoic” solid component (15%). The markedly hyperechoic solid component was seen in benign masses such as teratomas or endometriomas, and was specific for a benign etiology in this study. The study by Brown also concluded that an “abnormal amount” of free intraperitoneal fluid suggests malignancy. Furthermore, while thick septations have been described in association with malignant masses, malignant cystic masses can have no septations (1).
Color and spectral Doppler have been used to aid in determination of whether an ovarian mass is malignant. The study by Brown found that a mass with a nonhyperechoic solid component and central color flow was more likely to be malignant (60%) than benign (40%). (As this case shows, a fibroma is a solid benign mass that may have internal flow.) The masses with nonhyperechoic solid components and peripheral or no flow were benign in 81% of cases. Other studies have evaluated the utility of low impedance flow as an indicator that a mass is malignant (2,3). The data have demonstrated that benign masses typically have high-impedance flow and malignant masses low-impedance flow (2). However, the results of these studies show an overlap. Low impedance flow has been demonstrated in some benign lesions such as dermoids, cystadenomas, endometriomata, and “non-neoplastic cysts”, including a hemorrhagic corpus luteum cyst (2,3). Furthermore, a small number of malignant primary ovarian neoplasms demonstrated high-impedance flow in both of these studies.
In making the determination of whether a mass is benign or malignant, consideration must be given to the appearance of the mass, presence of associated findings (such as increased peritoneal fluid) and the duplex and color Doppler flow patterns. In this case, the right ovarian mass contained a solid component that was not markedly hyperechoic and contained central flow, findings suggestive of malignancy. 3D pelvic sonography confirmed the presence of papillary excrescences seen on 2D. The role of 3D pelvic sonography in the evaluation of pelvic masses is being actively investigated (4). It can provide confirmatory evidence of the location and internal consistency of many pelvic masses. Color Doppler sonography yielded additional information suggesting malignancy, by demonstrating low impedance flow within the papillary excrescences. At pathology, the right adnexal mass was found to be a borderline serous papillary tumor.
The left adnexal mass was found to represent an ovarian fibroma, a rare stromal tumor of the ovary. Its appearance is similar to uterine fibroids. Rarely, fibromas are associated with ascites and left hydrothorax (Meig's syndrome).