B‐mode and Doppler features of struma ovarii

Mature teratomas are relatively common ovarian tumors that exhibit a variable sonographic appearance, due to their heterogeneous histological components1. Caspi et al. proposed some pathognomonic echo patterns for the sonographic diagnosis of this tumor2. The agreement between these pathognomonic echo patterns and postoperative histological diagnosis has been reported to be as high as 97.45%2. Struma ovarii are rare ovarian tumors, considered as variants of mature teratomas, in which more than 50% of the neoplastic tissue is generally thyroid tissue3. Little has been reported on the sonographic appearance of this tumor4. We therefore reviewed clinical and sonographic data on a series of histologically confirmed cases of struma ovarii (n = 9) and mature teratoma (n = 120) surgically removed at our institution over the last 10 years, in order to determine whether there were any differences in their morphological and vascular ultrasound patterns. All patients were evaluated prior to surgery by transvaginal color Doppler ultrasound, using a Toshiba SSA-360 (Toshiba Systems, Tokyo, Japan) or a Voluson 730 (GE Medical Systems, Milwaukee, WI, USA) machine. Our standard scanning protocol has been reported elsewhere5. We considered ultrasound patterns to be ‘typical’ of mature teratomas when one of the following features was present in the sonogram: mass of heterogeneous echogenicity with associated shadowing, echogenic thin band-like echoes or fat/fluid level. Cases in which none of these patterns was found were considered to be ‘atypical’. The presence or absence of intratumoral vascularization was determined using color Doppler. When present, its location was described as peripheral or central5. Serum CA 125 levels were also determined. There were no statistical differences between the groups with respect to mean age, menopausal status, patients' symptoms and CA 125 levels (P ≥ 0.05) (Table 1). The incidence of struma ovarii (as a proportion of teratomas) found in our study was higher than that reported in the literature (7.0% vs. 5%). Typically, struma ovarii occurs in premenopausal asymptomatic women who are diagnosed incidentally as having a unilateral mass with negative tumor markers2. B-mode and Doppler findings in the two groups are shown in Table 1. Sometimes struma ovarii showed one of the characteristic sonographic patterns of mature teratomas2, but in most cases (67%, 6/9 cases) they showed an atypical multilocular cystic-solid ultrasound appearance, without acoustic shadowing and with central vascularization (Figures 1 and 2). Thus, the echo patterns of struma ovarii generally differed from those of mature teratomas. Furthermore, when blood flow within the tumor was found, vessels tended to be located centrally, i.e. within the solid areas6. Therefore, struma ovarii are a possible source of false positives when discriminating benign from malignant adnexal masses by transvaginal color Doppler ultrasound, because a multilocular solid appearance with central vascularization is found in many cases of ovarian cancer7, 8. Characteristic B-mode ultrasound findings of struma ovarii: a multilocular cystic-solid mass is visible. Transvaginal color Doppler image of a struma ovarii: centrally located vessels are visible within solid areas. P. Royo*, J. L. Alcazar*, M. Virgen , J. Mazaira*, M. Jurado*, G. Lopez*, * Department of Obstetrics and Gynecology, Clinica Universitaria de Navarra, Universidad de Navarra, Avda.