Cellular congenital mesoblastic nephroma detected by prenatal MRI: a case report and literature review

Abstract

Congenital mesoblastic nephroma (CMN) is a rare tumor, yet it is the most frequently diagnosed renal neoplasm in the first 3 months of life. CMN reports with prenatal magnetic resonance imaging (MRI) are scarce. Our aims were to describe a case with fetal MR imaging along with other findings, and to review the literature concerned with prenatal MRI detection of CMN. Upon routine ultrasound (US) examination of a 36-week pregnant woman, a fetal abdominal mass was disclosed. Prenatal MRI revealed a large, well-circumscribed renal mass of solid and cystic components, not invading the adjacent tissues, but compressing normal renal parenchyma of the lower pole of the left kidney. Thus, a low malignant renal tumor was considered. After Cesarean delivery, imaging including US and computerized tomography (CT) scan was performed on the apparently healthy boy and verified the prenatal MRI finding. Accordingly, left nephrectomy was performed at the age of 12-day. The pathology confirmed CT results of the solid and cystic components of the mass, in addition to the necrotic and hemorrhagic constitution. Cellular CMN was diagnosed, and ETV6 gene rearrangement was demonstrated by FISH analysis. No recurrence was detected within the 40 months follow-up after the operation. Our report described a rare and seldomly detected renal tumor in utero with the aid of MRI and reviewed the few related reports in the literature in which MRI was performed prenatally. This report also highlights the need for prenatal MRI as a complementary tool to US in cases with suspected fetal renal mass and recommends its use for carefully managing the possible risks during the perinatal period.

How to improve initial diagnostic accuracy of kidney tumours in childhood?—A non‐invasive approach

“…No CMN patient of our cohort had metastasis, confirming the very low metastatic risk of this tumour 18 . Nevertheless, CMN with distant metastases has been reported in rare cases, mainly in association with the cellular subtype 22–24 . Compared to previous studies, we found a higher risk of distant metastasis for CCSK (13% vs. 4%–7%) 15,17 .…”

“…18 Nevertheless, CMN with distant metastases has been reported in rare cases, mainly in association with the cellular subtype. [22][23][24] Compared to previous studies, we found a higher risk of distant metastasis for CCSK (13% vs. 4%-7%). 15,17 The association of older age, larger TV and more advanced tumour stage in our series of WT was recently also reported in a large SEER cohort of 3463 patients 25 (Supplemental Consistent with previous work, we identified CMN as the most common kidney tumour up to 3 months of age.…”

Diagnostic magnetic resonance imaging characteristics of congenital mesoblastic nephroma: a retrospective multi-center International Society of Pediatric Oncology-Renal Tumor Study Group (SIOP-RTSG) radiology panel study

“…Congenital mesoblastic nephroma as a separate entity was first described by Bolande et al and classified as a benign renal tumor [ 9 , 10 ]. Nevertheless, given limited reports of metastatic behavior, it is currently best classified as a mesenchymal tumor with low malignant potential [ 2 , 5 , 11 – 14 ]. Morbidity and mortality are predominantly caused by associated polyhydramnios and other related paraneoplastic syndromes at presentation, whereas the tumor rarely metastasizes, mainly to the lungs, brain, liver, or bone [ 11 , 15 – 20 ].…”

“…Based on previous case reports and small retrospective studies, congenital mesoblastic nephroma is typically described as homogeneous and isointense to normal renal parenchyma [ 4 , 7 , 12 , 14 , 33 ]. The cellular type seems to be more heterogeneous, making differentiation from malignant tumors more difficult [ 3 , 6 , 8 , 21 , 28 , 33 – 37 ].…”

Prenatal Course and Sonographic Features of Congenital Mesoblastic Nephroma

“…CMN can be prenatally diagnosed by ultrasound and MRI. Several case/series reports of the prenatal diagnosis of CMN have been scatteringly published in the literature, and they are increasing in number [ 2 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ]. However, to the best of our knowledge, the prenatal features and outcomes of pregnancies with fetal CMN have never been systematically reviewed and analyzed, whereas neonatal and pediatric series have been published several times.…”