Fetal congenital mesoblastic nephroma: analysis of three cases / 中华围产医学杂志

ABSTRACT

Objective:To analyze the characteristics of prenatal MRI and postnatal CT images of fetal congenital mesoblastic nephroma (CMN).Methods:We retrospectively recruited three women with a singleton pregnancy suspected of having fetal CMN by prenatal imaging examination and confirmed by postpartum surgical resection and pathological examination at Guangzhou Women and Children Medical Center from August 2017 to April 2019. The prenatal MRI, postnatal CT, and pathological examination data were analyzed to summarize the image features of fetal CMN using descriptive statistical analysis.Results:(1) The total number of deliveries in the setting during the same period was 57 716, and the incidence of CMN was 0.005% (3/57 716). All the cases were male and born through cesarean section due to polyhydramnios for case 1 and 2 and sudden fetal distress, fetal pericardial effusion with enlarged mass in the third trimester for case 3. (2) Prenatal MRI examination found that the lesions in case 1 and 3 were located in the left kidney, and in the right kidney in case 2. The tumors in the three cases were all around with clear borders and hyperintense signal on T2-weighed imaging (T2WI). Iso-signal on T1WI was noted for case 1 and 2, a slightly hypointense signal on T1-weighed imaging (T1WI), and a hyperintense signal on diffused weighed imaging were noted for case 3. (3) Postnatal CT plain scan showed uniform density tumor in cases 1 and 2 with "packing sign" in CT enhancement. Non-uniform density, internal, larger and high-density bleeding tumor was found in case 3, and the CT enhancement manifested as nodular, non-uniform, and intratumoral bleeding. (4) Postoperative pathological examination revealed that cases 1 and 2 were classic types, and case 3 was cellular type.Conclusions:In this study, the prenatal MRI characteristic of CMN is a uniform signal, iso-signal on T1WI for classic type and non-uniform signal, and reduced signal on T1WI for cellular type. In classic type cases, postnatal CT enhancement showed a "packing sign." In contrast, in cellular type cases, the CT plain scan is manifested as non-uniform, intratumoral bleeding, and the enhancement pattern showed nodular and non-uniform enhancement. However, the results of this study is limited due to the small sample size and studies with larger sample size is needed in the future.