Abstract
Mesoblastic nephroma is a mesenchymal neoplasm that arises from the metanephric blastema. This mass represents 80% of solid renal masses in neonates. We present a 23yo G3P2 Native American female initially referred at 24 weeks due to an enlarged uterus. On 2D and 3D ultrasound exam, a male fetus was noted to have a 4cm×5cm solid tumor in the right retroperitoneal space and polyhydramnios. By 28 wks, the mass had increased to 8×6cm with more extreme polyhydramnios. The mass originated in the renal fossa and extended to the level of the diaphragm superiorly and across the midline. The mass replaced the fetal right kidney. The left kidney appeared normal. Premature labor initiated hospitalization. A series of drainage amniocentesis were performed due to extreme polyhydramnios and preterm labor. Chromosome analysis on the fluid showed a normal male karyotype, 46, XY. Multiple 2D and 3D images were obtained on this patient. She delivered at 33wld by cesarean section due to sudden labor and dilitation. Surgical resection was performed on day 5. The mass measured 10×10cm at birth. The diagnosis of mesoblastic nephroma, with classic morphology was confirmed by histopathology. Cytogenetic studies on cells from short term cultures showed a hyperdiploid male karyotype with extra copies of chromosomes 7,8,11, 16, and 17. Trisomy 16 was observed as the sole abnormality in two cells from one isolated area. Nonrandom chromosome abnormalities of trisomy 11, 8 and 7 have been reported for several cases of mesoblastic nephroma. Trisomy 11 is most commonly associated with cellular or mixed histology, unlike this specimen. Parental origin of the extra copy of 11 and the relationship to renal tumor etiology is of interest and molecular studies are in progress for this case. The combination of three-dimensional ultrasound, pathology and genetic studies has facilitated diagnosis, treatment and further investigation of this rare prenatal presentation of a congenital renal tumor.
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Jackon, D., Haag, M., Brown, L. et al. Congenital mesoblastic nephroma: perinatal, surgical and genetic features and associated 2D and 3D imaging. Genet Med 2, 110 (2000). https://doi.org/10.1097/00125817-200001000-00216
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DOI: https://doi.org/10.1097/00125817-200001000-00216