Case Report:Prenatal sonographic diagnosis of a fetal renal mesoblastic nephroma occurring after transfer of a cryopreserved embryo

Here we report the first case of prenatally diagnosed fetal renal mesoblastic nephroma occurring after transfer of a cryopreserved embryo. A 37 year old woman, having immunological infertility, was treated by in-vitro fertilization (IVF) and embryo transfer. Following unsuccessful IVF using fresh embryos, the patient conceived after transfer of cryopreserved-thawed embryos. The chromosomal analysis identified a normal karyotype at 16 weeks' gestation when amniocentesis was performed. The pregnancy course was uneventful until 28 weeks' gestation when polyhydramnios associated with fetal renal tumour was detected using ultrasonography. A male infant weighing 2564 g was born via Caesarean section at 34 weeks' gestation. A left nephrectomy was performed 5 days after delivery and the tumour was identified histologically as a mesoblastic nephroma. The postoperative course was uncomplicated to this point.