Managing a case of Breus' mole with severe fetal growth restriction via sequential ultrasonographic imaging and MRI.

A Breus' mole is a massive subchorionic thrombohematoma that arises below the chorionic plate on the fetal side of the placenta. It requires careful perinatal management because of the associated high incidence of severe fetal growth restriction and intrauterine fetal demise. However, the mechanism of its development remains unclear, and there are no reports examining the continuous changes in the hematomas. Herein, we report a case of a Breus' mole in which ultrasonographic massive subchorionic thrombohematoma changes were observed during pregnancy. A 40-year-old pregnant patient presented with fetal growth restriction, a hematoma with a highly echoic lesion, and an extremely thickened placenta. The clinical picture of massive subchorionic thrombohematoma gradually changed from a high-echoic phase with a 7-cm thick placenta to a high- and low-echoic mixed phase to a completely low-echoic phase with a prominent atrophic placenta (placental thickness = 3.5 cm) in almost 8 weeks. At 34 weeks of gestation, a male infant was delivered via cesarean section due to its nonreassuring fetal status with extremely low birth weight (1230 g). Postpartum histological findings revealed the presence of a Breus' mole. In conclusion, we observed the ultrasonographic changes of the massive subchorionic thrombohematoma that were detected as a placental hemorrhagic infarction by magnetic resonance imaging, from a high- to low-echoic area. The clinical course from massive subchorionic thrombohematoma to Breus' mole may be a prominent atrophic change in the placental tissue during pregnancy. These sequential ultrasonographic findings could be a key factor in understanding the pathophysiology of Breus' moles.