During organogenesis, a number of genes of the WNT family  like the WNT4 are activated, producing the necessary signals to conduct the development of the mullerian structures. That is the reason why mutations in the WTN-4 gene cause müllerian duct regression . Recent research has underlined the possibility that, on the other extreme, müllerianosis might be caused by the abnormal reactivation of these genes [26, 27], causing metaplasia of normal tissues like the peritoneum. This would explain why these anomalies appear disseminated in the pelvic and abdominal organs [28, 29] or why Box-8 (PAX8) positive cells appear so frequently in peritoneal washing for diverse gynecological indications . However it is true that another possibility for these findings would be the presence of remnants of müllerian precursor cells included within the developing tissues. Be that as it may, these cells are sensitive to estrogen and progesterone and might proliferate during pregnancy increasing the volume of cyst and thus making them detectable at the end of pregnancy. However, the fact that the lesions did not disappear after pregnancy makes this possibility less likely. In summary, cystic endosalpingiosis is a benign condition that should always be considered, even in pregnancy, when it comes to making the differential diagnosis of a pelvic or systemic multicystic mass.