Decidualized ovarian endometriosis in pregnancy: a challenging diagnostic entity.

BACKGROUND The hormonal milieu that characterizes pregnancy may determine profound modifications of ovarian endometriomas leading to lesions mimicking malignancy. In this study, we report on our experience and perform a review of the literature on this issue. METHODS Data from women evaluated at our referral center for prenatal diagnosis were reviewed in order to identify those who were detected with an ovarian endometrioma in pregnancy mimicking malignancy. A review of the literature on this issue (1990-2008) was also performed, using the PubMed database. RESULTS Three cases were identified at our center. The literature reports on a further 19 cases (11 studies). Sonographic and color Doppler examination consistently documented rapidly growing and abundantly vascularized intracystic excrescences. Conversely, the presence of septations or significant free fluid was never reported. The vast majority of cases underwent surgical removal. Interestingly, in our experience, in a woman who declined surgery and had spontaneous miscarriage at 10 weeks' gestation, the sonographic examination performed 6 weeks after dilatation and curettage revealed an unremarkable typical endometrioma, thus suggesting that it is a transitory transformation. CONCLUSIONS Pregnancy-related modifications of an ovarian endometrioma leading to the rapid development of vascularized intracystic excrescences are an uncommon but possible event. An expectant management and serial monitoring should first be envisaged in these cases provided that other features of malignancy, such as septations or free fluid, are absent.