Prenatal differential diagnosis of complete hydatidiform mole with a twin live fetus and placental mesenchymal dysplasia by magnetic resonance imaging

Aim To assess the use of magnetic resonance imaging (MRI) for prenatal differentiation between complete hydatidiform mole with a twin live fetus (CHMTF) and placental mesenchymal dysplasia (PMD). Methods Three CHMTF cases and three PMD cases, from two institutions over a 6-year period, were retrospectively included in this study. Clinical findings including age, pregnancy history, serum hCG level, ultrasonography findings, complications of the mother, outcome of the fetus, and results of chromosomal study of fetus, amniotic fluid and lesion, if possible, were noted. MRI findings were evaluated by two radiologists with respect to the location of the disease (intra- or extra-fetal sac), the presence of multicystic component, and presence of intra- or extra-lesional hemorrhage. Results In all six cases, the diseases were recognized as multicystic lesions by ultrasonography and MRI. In two of three CHMTF cases, patients continued with the pregnancy, which resulted in spontaneous abortion. In one case of CHMTF, the patient underwent artificial abortion, after which the mole progressed into an invasive mole with lung metastases. All three PMD patients had live births, and two of the three babies had fetal growth restriction. By MRI, CHMTF was located within an extra-fetal sac accompanied by intra- and/or extra-lesional hemorrhage, while PMD was located within the placenta in the fetal sac without hemorrhage. Conclusion MRI could provide important information about the prenatal differential diagnosis of CHMTF and PMD, based on the pathophysiology and characteristics of the diseases.