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

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.

Prenatal diagnosis of congenital mesoblastic nephroma

Congenital mesoblastic nephroma is a rare renal tumor that is diagnosed during pregnancy and is associated with polyhydramnios, prematurity, and neonatal hypertension. Differential diagnoses include Wilms tumor, adrenal neuroblastoma, and other abdominal tumors. We report a case of congenital mesoblastic nephroma detected by prenatal ultrasonography as a large fetal renal mass with polyhydramnios at 32 weeks of gestation. Ultrasonography showed a 6x6-cm complex, solid, hyperechoic, round mass in the right kidney. At 35 weeks of gestation, the patient was admitted with preterm premature rupture of membranes and the baby was delivered vaginally. Postnatal ultrasonography and computed tomography showed a heterogeneous solid mass on the right kidney. At the end of the first week of life, a right nephrectomy was performed and subsequent pathological examination confirmed a cellular variant of congenital mesoblastic nephroma with a high mitotic count. Postoperative adjuvant chemotherapy was administered. The newborn was discharged in good condition.

Mixed Epithelial and Stromal Tumor of the Kidney: A Case Report

The descriptive term "mixed epithelial and stromal tumor of the kidney" was recently proposed for a group of renal tumors characterized histologically by a mixture of stromal and epithelial proliferation. It is a rare benign neoplasm of the kidney which has been reported under various names such as adult type mesoblastic nephroma or others. We report a case of mixed epithelial and stromal tumor in a 47 yr old female patient presenting as a partly cystic and partly solid renal mass. Microscopically, the tumor exhibited spindle cell component in solid portion and epithelial proliferation around microcystic areas. Immunoreactive profiles and ultrastructural examination suggested myofibroblastic nature of the stromal cells. We believe this case exemplifies a unique adult renal tumor displaying both epithelial and stromal neoplastic component and has a few unusual features worthy of attention.