A case report of congenital mesoblastic nephroma detected during routine antenatal ultrasound scan
Published Date: 17th October 2025
Publication Authors: Boughey. S, Chados. N, McDowell. F
Case Report
We present a case report of a congenital mesoblastic nephroma (CMN) detected during routine antenatal ultrasound scan. This is a rare renal tumour of the fetus, that can be diagnosed during pregnancy, representing 2–4% of all paediatric renal tumours. This case was diagnosed in the third trimester on a routine placental localisation scan, the patient had polyhydramnios and an enlarged right fetal kidney. The patient was referred to the fetal medicine unit. The tumour was seen to be contained within a well-defined and intact capsule, blood flow originating from the renal artery was seen to be supplying the mass and it appeared to be very well vascularized giving a ‘ring of fire sign’. The possibility of CMN was counselled about. The baby was born prematurely at 33/40 by caesarean section following premature rupture of membranes and spontaneous labour. Despite suffering with associated paraneoplastic syndromes of hypertension and hypercalcaemia, the baby recovered well following a radical nephrectomy.
Discussion
Our case illustrates the importance of further assessment of fetal anatomy in all third trimester ultrasound scans, including those with polyhydramnios. Ultrasound features included a heterogeneous texture with a similar echogenicity to the liver. Congenital mesoblastic nephroma can be associated with complications including polyhydramnios and preterm labour and antenatal detection provides the opportunity for multidisciplinary team discussions and anticipatory planning, aiming for delivery in a tertiary centre. The prognosis is excellent with 95% five-year survival rate.
Boughey, S; Chados, N; McDowell, F et al. (2025). A case report of congenital mesoblastic nephroma detected during routine antenatal ultrasound scan. BJOG An International Journal of Obstetrics and Gynaecology. 132(S6), p.40. [Online]. Available at: https://doi.org/10.1111/1471-0528.18234 [Accessed 30 October 2025]
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